Articles |
From the Departments of Internal Medicine and Pharmacology (D.D.H., F.M.F.), Cardiovascular Center, University of Iowa College of Medicine, Iowa City.
Correspondence to Donald D. Heistad, MD, Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, Iowa 52242-1081.
| Abstract |
|---|
|
|
|---|
Key Words: gene knockout aorta atherosclerosis acetylcholine hypercholesterolemia
| Introduction |
|---|
|
|
|---|
Atherosclerosis impairs endothelium-dependent relaxation in diet-induced experimental animal models1 2 3 4 15 and in human arteries with atherosclerosis.16 17 18 19 It is not known whether hyperlipidemia produced by selective gene knockouts is associated with vascular dysfunction. Hence, we examined the hypothesis that endothelium-dependent relaxation is impaired in two nondietary, genetic models of hypercholesterolemia: apoE-knockout and combined apoE/LDL receptorknockout mice. To determine whether alterations in endothelium-dependent relaxation are a diffuse abnormality produced by hypercholesterolemia per se or are confined to those vessels that contain atherosclerotic lesions, we compared responses of the proximal (atherosclerotic) and distal segments of the thoracic aorta, where intimal thickening was minimal or absent. Our goal was to examine vascular responses in genetic models of atherosclerosis. We examined vascular responses in two animal models that have different degrees of atherosclerosis.
Finally, we examined structural changes in the atherosclerotic aorta to determine whether vascular "remodeling" had occurred. In remodeling during atherosclerosis, intimal thickening is associated with outward displacement of the vessel wall so that the vascular lumen is relatively preserved.20 21 22 Vascular remodeling has been observed in diet-induced atherosclerosis in experimental animals and in coronary arteries of humans with atherosclerosis20 21 22 but has not been described in a genetic model of atherosclerosis.
| Methods |
|---|
|
|
|---|
Vascular Ring Preparation
Studies were performed on aortic rings in vitro. On the day of
the study, the mouse was anesthetized with sodium pentobarbital
injection (0.2 mg/g body weight), and the thoracic aorta was
removed and immediately placed in Krebs' buffer of the following ionic
composition (mmol/L): NaCl 118.3, KCl 4.7, CaCl2 2.5,
MgSO4 1.2, KH2PO4 1.2,
NaHCO3 25, and glucose 12. Loose connective tissue in the
adventitia was removed carefully to avoid damage to the
endothelial surface, and the vessel was cut into rings
(3 to 4 mm long) from the ascending aorta and distal thoracic
aorta. Typically, four rings per mouse were studied. Aortic rings were
mounted on stainless steel hooks and suspended in vertical organ baths
containing 25 mL Krebs' solution maintained at 37°C and aerated with
a mixture of 95% O2 and 5% CO2. The rings
were connected to force transducers to measure isometric tension.
Resting tension was gradually increased to reach the final tension of
0.5 g, and the rings were allowed to equilibrate for at least 90
minutes and washed at 20-minute intervals. The rings were left at this
optimal resting tension throughout the remainder of the study.
Protocols
Aortic segments were precontracted by using a
thromboxane analogue [U46619
(9,11-dideoxy-11a,9a-epoxy-methanoprostaglandin
F2
)]. After stabilization at submaximal contraction
(~50% of maximum), responses to cumulative concentrations of
acetylcholine and nitroprusside were tested both in the presence and
absence of an inhibitor of nitric oxide synthase
L-NNA (100 µmol). Responses to cumulative concentrations
of calcium ionophore A23187 were also studied. Between each
concentration-response curve, the vessels were washed at least three
times with fresh Krebs' buffer and allowed to reequilibrate.
To evaluate a possible contribution of superoxide anion radicals to endothelial dysfunction, we studied responses to acetylcholine and nitroprusside in the presence of SOD (100 U/mL). We also studied responses to acetylcholine in the aorta from apoE/LDL receptordeficient mice that had been injected with PEG-SOD for 5 days (50 U · g-1 · d-1).3
Drugs
Acetylcholine, sodium nitroprusside, L-NNA, SOD,
U46619, and calcium ionophore A23187 were obtained from Sigma Chemical
Co. Stock solution (1 mmol) of A23187 was prepared by dissolving the
drug in 50% DMSO and 50% isotonic saline. Stock solution of U46619
was prepared by dissolving it in ethanol, and subsequent dilutions were
made in isotonic saline. All other drugs were dissolved and diluted in
isotonic saline. All concentrations are expressed as the final
concentration of each drug in the organ bath.
Assessment of Atherosclerosis
After completion of the experiment, proximal and distal segments
of thoracic aorta were fixed in formalin, and 8- to 10-µm sections
were cut and stained with VerhoeffVan Gieson's, and
hematoxylin/eosin stains. We obtained five rings from anatomically
constant sites: one from the midpoint of the ascending aorta (
2
mm from the aortic valve), one from the midaortic arch (midway between
the innominate and left carotid artery), and three rings from the
descending thoracic aorta (
1, 4, and 7 mm from the distal to
the subclavian artery). Four of the five rings (excluding the one from
the midaortic arch) that were used for morphometry were also used for
studies of vascular reactivity. For morphometry, we obtained samples
from normal (n=17), apoE-knockout (n=15), and apoE/LDL
receptorknockout (n=28) mice. Morphometric (quantitative)
determination of the size of the intima and media was performed with an
image analyzer as described previously.20 24 In
brief, the cross-sectional areas of the intima and media were
projected and digitized. To determine the luminal area, the
cross-sectional area enclosed by the internal elastic lamina was
corrected to a circle by applying the form factor
l2/4
to the measurement of the internal
elastic lamina, where l is the length of the lamina; the luminal area
was calculated as the difference between the corrected area within the
internal elastic lamina and the intimal area.
Statistical Analysis
All data are expressed as mean±SE; n indicates the number of
animals. Relaxation responses to acetylcholine, A23187, and sodium
nitroprusside were expressed as the percent relaxation from the amount
of precontraction produced by U46619. The response was recorded as
the cumulative relaxation response at each dose, expressed as a
percentage of the initial precontraction tension. The EC50
values were calculated by using a computer program that assumes a
linear curve between two points around 50% of the maximum response.
Comparisons were made using either a paired or unpaired Student's
t test. The Bonferroni correction was used for multiple
comparisons. Statistical significance was accepted at
P<.05.
| Results |
|---|
|
|
|---|
|
Morphometry and Histology
There was marked thickening of the intima-media of the proximal
(ascending) aorta of apoE/LDL receptordeficient mice, and minimal
(size) atherosclerotic lesions of the proximal (ascending) thoracic
aorta from apoE-deficient mice (Figs 2
and 3
). No
intimal thickening or lesions were observed in the aortas of normal
mice (Fig 3
). Despite intimal thickening in apoE/LDL receptorknockout
mice and marked differences in the severity of
atherosclerosis, the area of the lumen was similar in
the proximal thoracic aortas from normal, apoE-deficient, and
atherosclerotic apoE/LDL receptordeficient mice (Fig 3
).
|
|
There were minimal or no atherosclerotic lesions in the distal segments of thoracic aortas from apoE/LDL receptorknockout mice. The area of the vascular lumen was similar in distal segments of thoracic aortas of normal (0.38±0.02 mm2), apoE-knockout (0.42± 0.03 mm2), and apoE/LDL receptorknockout (0.36±0.02 mm2) mice.
Responses to U46619
The optimal resting tension in all groups of mice was 0.5 g.
The maximal response to U46619 was 1.41±0.05 g in the normal aortas,
similar in aortas from apoE-deficient mice, and smaller in the proximal
segments of thoracic aortas of apoE/LDL receptordeficient mice
(0.92±0.08 g, P<.05). The EC50 for contraction
with U46619 was -7.74±0.06 in normal mice and was not significantly
different in vessels from apoE-deficient or apoE/LDL
receptordeficient mice.
Responses in Normal C57BL/6J Mice
In vessels from normal mice, acetylcholine produced
concentration-dependent relaxation (Fig 4
), and the response was
similar in both proximal and distal segments of the thoracic aorta (Fig 5
). Relaxation to acetylcholine was
similar in female and male mice (data not shown). Relaxation to A23187
and nitroprusside was also similar in proximal and distal segments of
thoracic aortas of normal mice (Fig 5
).
|
|
In normal mice, relaxation to acetylcholine was markedly attenuated by L-NNA (100 µmol), a nitric oxide synthase inhibitor (P<.05). Maximum relaxation in response to acetylcholine was 76±5% and 38±4% in the absence and presence of L-NNA, respectively. L-NNA did not inhibit but instead enhanced (produced a leftward shift of the dose-response curve) responses to sodium nitroprusside in the normal mouse aorta (P<.05). The EC50 for nitroprusside was -7.62±0.13 and -8.24±0.10 in the absence and presence of L-NNA, respectively.
Responses in ApoE-Knockout Mice
In apoE-knockout mice, relaxation in response to acetylcholine and
nitroprusside in the proximal segments of the thoracic aorta, which had
minimal or no intimal thickening, was similar to that of the distal
segments of the thoracic aorta (Fig 6
).
Relaxation was similar to that in normal mice (Fig 5
). The
EC50 for relaxation with acetylcholine and nitroprusside
was similar in the aortas of normal and apoE-deficient mice
(Table
).
|
|
Relaxation to acetylcholine was markedly attenuated by L-NNA in apoE-deficient mice (data not shown). Thus, vasorelaxation in response to acetylcholine was mediated by nitric oxide in apoE-knockout mice as well as in normal mice. Similar to its effects on the normal aorta, L-NNA enhanced the response to sodium nitroprusside in aortas of apoE-knockout mice (data not shown).
Responses in ApoE/LDL ReceptorDouble-Knockout Mice
In apoE/LDL receptormutant mice, relaxation to acetylcholine was
markedly impaired in the proximal segments of the thoracic aorta, which
had atherosclerotic lesions when compared with the distal segments of
thoracic aorta, which had minimal or no intimal thickening (Figs 4
and 7
). In response to acetylcholine,
relaxation of proximal segments of thoracic aortas of apoE/LDL
receptorknockout mice was significantly impaired when compared with
proximal segments of thoracic aortas of either normal or apoE-knockout
mice (Figs 4 through 6![]()
![]()
). Impairment of relaxation to acetylcholine in
the proximal thoracic aorta of apoE/LDL receptorknockout mice was
similar in female and male mice (data not shown). Relaxation of the
proximal (atherosclerotic) segments of the thoracic aorta in response
to A23187 was markedly impaired compared with distal segments of the
thoracic aorta of apoE/LDL receptordeficient mice or normal mice (Fig 7
).
|
In the proximal (atherosclerotic) segments of thoracic aortas of
apoE/LDL receptordeficient mice, relaxation in response to sodium
nitroprusside was attenuated (Fig 7
). Relaxation to sodium
nitroprusside in distal segments of thoracic aortas of apoE/LDL
receptorknockout mice was similar to that of normal and
apoE-deficient mice. The EC50 for relaxation in response to
sodium nitroprusside was similar in all three groups of mice (data not
shown).
As in normal and apoE-deficient mice, relaxation of the distal segments of thoracic aortas in response to acetylcholine was markedly attenuated in the presence of L-NNA in apoE/LDL receptorknockout mice. L-NNA did not inhibit but enhanced (produced a leftward shift of the dose-response curve) responses to sodium nitroprusside in both normal and atherosclerotic segments of thoracic aortas (data not shown).
Effect of SOD
In vitro incubation of the atherosclerotic segments of thoracic
aortas from apoE/LDL receptordeficient mice with SOD (100 U/mL) for
30 minutes did not significantly influence
endothelium-dependent relaxation (maximum relaxation in
response to acetylcholine, 33±7%). In apoE/LDL receptordeficient
mice (n=3) injected with PEG-SOD (for 5 days), relaxation of the
proximal atherosclerotic segments of the thoracic aorta in response to
acetylcholine (maximum relaxation in response to acetylcholine,
12±7%) was not improved.
| Discussion |
|---|
|
|
|---|
Endothelium-Dependent Relaxation
There have been few studies that have examined
endothelium-dependent relaxation of mouse vessels in
vitro. In normal mice, we found that acetylcholine produced relaxation
that was markedly attenuated by the nitric oxide synthase
inhibitor L-NNA. Thus, relaxation of the normal
mouse aorta in response to acetylcholine is mediated in large part by
nitric oxide.
Mechanisms that produce impaired endothelial function in atherosclerosis are not completely clear. One possibility is that smaller quantities of nitric oxide are produced by atherosclerotic vessels in response to endothelium-dependent stimuli. This seems unlikely, because levels of mRNA and protein for the endothelial isoform of nitric oxide synthase (NOS III) and the production of nitric oxide in the atherosclerotic rabbit aorta appear to be increased rather than decreased.25 26 We found that vasorelaxation in response to both acetylcholine and A23187 was impaired in the proximal aortas of apoE/LDL receptordeficient mice, which contained atherosclerotic lesions. Impairment of responses to A23187 suggests that endothelial dysfunction extends beyond muscarinic receptors in this genetic model.
A second possible mechanism of impairment of endothelial function relates to degradation and/or inactivation of nitric oxide by superoxide anion. Incorporation of lipids within the endothelium, an early manifestation of atherosclerosis, and associated oxidative processes may be responsible for the degradation of nitric oxide. For example, increased production of superoxide anion in atherosclerotic arteries has been detected in several studies.4 27 28 Nitric oxide is rapidly inactivated by superoxide anion.29 30 The reaction of nitric oxide and superoxide anion occurs even more rapidly than the reaction of superoxide anion with SOD.29 30
A third possibility is impaired response of vascular muscle to nitric oxide. Relatively normal relaxation in response to sodium nitroprusside in normal and atherosclerotic vessels suggests that the guanylate cyclase/cGMP system is intact in vascular muscle. The slightly diminished relaxation of atherosclerotic segments of thoracic aortas from apoE/LDL receptordeficient mice in response to sodium nitroprusside may be attributed to the severity of the lesion.
Some3 5 31 but not all32 33 studies have shown that impaired endothelium-dependent responses during hypercholesterolemia and/or atherosclerosis can be restored toward normal by SOD. In the present study, endothelium-dependent relaxation of the proximal atherosclerotic segments of thoracic aortas of apoE/LDL receptordeficient mice was not improved by acute or chronic (5-day) treatment with SOD. We cannot exclude the possibility that the dose or duration of SOD administration was not sufficient. Nevertheless, this finding is similar to that in a recent study in patients32 and suggests that either generation of superoxide anion is not important in this model or that exogenously administered SOD may be unable to reach the site of formation of superoxide anion. Because of the extremely efficient reaction of superoxide anion and nitric oxide,29 30 SOD needs to be present at the site of superoxide radical generation to protect nitric oxide.30 Thus, our studies do not exclude a role for enhanced generation of superoxide anion as a mediator of vascular dysfunction during atherosclerosis.
We found that responses to acetylcholine did not differ in female and male mice. This finding in normal and atherosclerotic mice is different from previous reports in other species.34 35 36 37 38 It is possible that our observation is an artifact, because the number of females and males in each group was small. It is possible, however, that the finding is accurate for mice. In monkeys and rabbits, estrogen modulates vasomotion of atherosclerotic coronary arteries.35 36 Other studies indicate that in C57BL/6J mice, males are more resistant than females to hypercholesterolemia-induced atherosclerosis.39 A recent study demonstrated that basal release of endothelium-derived nitric oxide was significantly greater in the aortas of male (C57BL/6J) than in female mice.40 Thus, findings in previous studies39 40 and the present study may suggest that increased susceptibility to atherosclerosis in males, which is characteristic of several species, is not observed in C57BL/6J mice.
Severity of Atherosclerosis
A surprising finding in the present study is that intimal
thickening in the proximal segments of the thoracic aorta was much
greater in apoE/LDL receptorknockout mice than in apoE-knockout mice.
We used mice that were <20 weeks old, and our findings with
apoE-knockout mice are consistent with previous studies, which
observed only modest atherosclerosis in apoE-knockout
mice that were <20 weeks of age.9 10 In older
apoE-knockout mice fed a normal diet, extensive
atherosclerosis develops in the proximal segments of
the thoracic aorta.9 10 11 To our knowledge, similar studies
have not been performed previously in combined apoE/LDL
receptorknockout mice. Plasma cholesterol levels were
only modestly greater in apoE/LDL receptorknockout mice (18.0
mmol/L) than in apoE-knockout mice (14.9 mmol/L),
which is consistent with previous studies by Ishibashi et
al.12 Thus, it was surprising that intimal thickening was
12-fold greater in the double-knockout than the apoE-knockout
mice.
A possible explanation for the marked difference in development of atherosclerosis in apoE/LDL receptorknockout mice compared with apoE-knockout mice is the presence of a prominent population of cholesterol-rich LDL in apoE/LDL receptorknockout mice. Larger cholesterol-rich particles, which are known to resemble ß-VLDL, predominate in both hyperlipidemic models. However, LDLs are smaller than ß-VLDLs and consequently are more likely to penetrate the endothelium and deposit in the arterial wall. Another possibility is that the absence per se of LDL receptors in the vessels is atherogenic. The role of vascular LDL receptors in atherosclerosis is unclear. LDL catabolism by the intima has been shown to be predominant.34
The observation of vascular remodeling in atherosclerotic apoE/LDL receptorknockout mice is of interest. Several pathological processes in the intima-media of atherosclerotic arteries result in thickening of the vessel wall. In remodeling, the atherosclerotic vessel wall thickens, but there is outward displacement of the vessel wall so that the lumen is preserved. The area circumscribed by the internal elastic lamina increases as the area of the plaque contained within the lumen increases. In studies of atherosclerosis in nonhuman primates and in atherosclerotic human coronary arteries, maintenance of lumen size has been noted despite massive intimal thickening.20 21 22 Vascular remodeling is thought to require synthesis and reorganization of collagen and the extracellular matrix. Our observations indicate that the apoE/LDL receptorknockout mouse may be a useful model for future studies of this process.
In summary, the present study shows that atherosclerosis, which is more severe in combined apoE/LDL receptorknockout mice than in apoE-knockout mice, is associated with vascular remodeling and significant attenuation of the endothelial regulation of vascular tone. These studies of endothelial function in mice provide the foundation for additional studies of vascular biology in novel, genetically altered models.
| Selected Abbreviations and Acronyms |
|---|
|
| Acknowledgments |
|---|
Received November 4, 1996; accepted June 16, 1997.
| References |
|---|
|
|
|---|
2.
Freiman PC, Mitchell GC, Heistad DD, Armstrong ML,
Harrison DG. Atherosclerosis impairs
endothelium-dependent vascular relaxation to
acetylcholine and thrombin in primates. Circ Res.. 1986;58:783-789.
3.
Mugge A, Elwell JH, Peterson TE, Hofmeyer TG, Heistad
DD Harrison DG. Chronic treatment with polyethylene-glycolated
superoxide dismutase partially restores
endothelium-dependent vascular relaxations in
cholesterol-fed rabbits. Circ Res.. 1991;69:1293-1300.
4. Ohara Y, Peterson TE, Harrison DG. Hypercholesterolemia increases endothelial superoxide anion production. J Clin Invest.. 1993;91:2546-2551.
5.
Tagawa H, Tomoike H, Nakamura M. Putative
mechanisms of the impairment of endothelium-dependent
relaxation of the aorta with atheromatous plaque in
heritable hyperlipidemic rabbits. Circ
Res.. 1991;68:330-337.
6.
Taguchi H, Faraci FM, Kitazono T, Heistad DD.
Relaxation of the carotid artery to hypoxia is impaired
in Watanabe heritable hyperlipidemic rabbits.
Arterioscler Thromb Vasc Biol.. 1995;15:1641-1645.
7. Tagawa H, Tomoike H, Nakamura M. Putative mechanisms of the impairment of endothelium-dependent relaxation of the aorta with atheromatous plaque in heritable hyperlipidemic rabbits. Circ Res.. 1991;68:330-337.
8. Breslow JL. Mouse models of atherosclerosis. Science. 1996;272:685-688.[Abstract]
9.
Nakashima Y, Plump AS, Raines EW, Breslow JL, Ross R.
ApoE-deficient mice develop lesions of all phases of
atherosclerosis throughout the arterial
tree. Arterioscler Thromb.. 1994;14:133-140.
10.
Reddick RL, Zhang SH, Maeda N.
Atherosclerosis in mice lacking apo E:
evaluation of lesional development and progression.
Arterioscler Thromb.. 1994;14:141-147.
11.
Palinski W, Ord VA, Plump AS, Breslow JL, Steinberg D,
Witztum JL. ApoE-deficient mice are a model of lipoprotein
oxidation in atherogenesis: demonstration of oxidation-specific
epitopes in lesions and high titers of autoantibodies to
malondialdehyde-lysine in serum. Arterioscler
Thromb.. 1994;14:605-616.
12.
Ishibashi S, Herz J, Maeda N, Goldstein JL, Brown MS.
The two-receptor model of lipoprotein clearance: tests of the
hypothesis in "knockout" mice lacking the low density lipoprotein
receptor, apolipoprotein E, or both proteins. Proc Natl
Acad Sci U S A.. 1994;91:4431-4435.
13. Tangirala RK, Rubin EM, Palinski W. Quantitation of atherosclerosis in murine models: correlation between lesions in the aortic origin and in the entire aorta, and differences in the extent of lesions between sexes in LDL receptor-deficient and apolipoprotein E-deficient mice. J Lipid Res.. 1995;36:2320-2328.[Abstract]
14. Plump AS, Smith JD, Hayek T, Aalto-Setala K, Walsh A, Verstuyft JG, Rubin EM, Breslow JL. Severe hypercholesterolemia and atherosclerosis in apolipoprotein E-deficient mice created by homologous recombination in ES cells. Cell. 1992;71:343-353.[Medline] [Order article via Infotrieve]
15. Busse R, Fleming I. Endothelial dysfunction in atherosclerosis. J Vasc Res.. 1996;33:181-194.[Medline] [Order article via Infotrieve]
16. Ludmer PL, Selwyn AP, Shook TL, Wayne RR. Paradoxical vasoconstriction induced by acetylcholine in atherosclerotic coronary arteries. N Engl J Med.. 1986;315:1046-1051.[Abstract]
17.
Liao JK, Bettmann MA, Sandor T, Tucker JI, Coleman SM,
Creager MA. Differential impairment of vasodilator
responsiveness of peripheral resistance and conduit vessels
in humans with atherosclerosis. Circ
Res.. 1991;68:1027-1034.
18. Chester AH, O'Neil GS, Moncada S, Tadjkarimi S, Yacoub MH. Low basal and stimulated release of nitric oxide in atherosclerotic epicardial coronary arteries. Lancet. 1990;336:897-900.[Medline] [Order article via Infotrieve]
19. Zeiher AM, Drexler H, Saurbier B, Just H. Endothelium-mediated coronary blood flow modulation in humans: effects of age, atherosclerosis, hypercholesterolemia, and hypertension. J Clin Invest.. 1993;92:652-662.
20.
Armstrong ML, Heistad DD, Marcus ML, Megan MB, Piegors
DJ. Structural and hemodynamic responses of
peripheral arteries of macaque monkeys to atherogenic
diet. Arteriosclerosis. 1985;5:336-346.
21. Glagov S, Weisenberg E, Zarins CK, Stankunavicius R, Kolettis GJ. Compensatory enlargement of human atherosclerotic coronary arteries. N Engl J Med.. 1987;316:1371-1375.[Abstract]
22. Di Marion C, Ruygrok PN, Serruys PW. Vascular remodeling in coronary artery disease. J Cardiovasc Pharmacol. 1994;24(suppl 3):S5S15.
23. De Silva HV, Mas-Oliva J, Taylor JM, Mahley RW. Identification of apolipoprotein B-100 low density lipoproteins, apolipoprotein B-48 remnants, and apolipoprotein E-rich high density lipoproteins in the mouse. J Lipid Res.. 1994;35:1297-1310.[Abstract]
24.
Sobey CG, Faraci FM, Piegors DJ, Heistad DD.
Effect of short-term regression of
atherosclerosis on reactivity of carotid and retinal
arteries. Stroke.. 1996;27:927-933.
25. Kanazawa K, Kawashima S, Mikami S, Miwa Y, Hirata K, Suematsu M, Hayashi Y, Itoh H, Yokoyama M. Endothelial constitutive nitric oxide synthase protein and mRNA increased in rabbit atherosclerotic aorta despite impaired endothelium-dependent vascular relaxation. Am J Pathol.. 1996;148:1949-1956.[Abstract]
26. Minor R, Myers PR, Guerra R, Bates JN, Harrison DG. Diet-induced atherosclerosis increases release of nitrogen oxides from rabbit aorta. J Clin Invest.. 1990;86:2109-2116.
27. Mugge A, Brandes RP, Boger RH, Dwenger A, Bode-Boger S, Kienke S, Frolich JC, Lichtlen PR. Vascular release of superoxide radicals is enhanced in hypercholesterolemic rabbits. J Cardiovasc Pharmacol.. 1994;24:994-998.[Medline] [Order article via Infotrieve]
28. Boger RH, Bode-Boger SM, Mugge A, Kienke S, Brandes R, Dwenger A, Frolich JC. Supplementation of hypercholesterolaemic rabbits with L-arginine reduces the vascular release of superoxide anions and restores NO production. Atherosclerosis. 1995;117:273-284.[Medline] [Order article via Infotrieve]
29.
Beckman JS, Beckman TW, Chen J, Marshall PA, Freeman
BA. Apparent hydroxyl radical production by
peroxynitrite: implications for endothelial injury from
nitric oxide and superoxide. Proc Natl Acad Sci
U S A.. 1990;87:1620-1624.
30. Darley-Usmar V, Wiseman H, Halliwell B. Nitric oxide and oxygen radicals: a question of balance. FEBS Lett.. 1995;369:131-135.[Medline] [Order article via Infotrieve]
31.
White CR, Brock TA, Chang LY, Crapo J, Briscoe P, Ku D,
Bradley WA, Gianturco SH, Gore J, Freeman BA, Tarpey MM.
Superoxide and peroxynitrite in
atherosclerosis. Proc Natl Acad Sci
U S A.. 1994;91:1044-1048.
32. Garcia CE, Kilcoyne CM, Cardillo C, Cannon RO, Quyyumi AA, Panza JA. Evidence that endothelial dysfunction in patients with hypercholesterolemia is not due to increased extracellular nitric oxide breakdown by superoxide anions. Am J Cardiol.. 1995;76:1157-1161.[Medline] [Order article via Infotrieve]
33. Kamata K, Kojima S, Sugiura M, Kasuya Y. Preservation of endothelium-dependent vascular relaxation in cholesterol-fed mice by the chronic administration of prazosin or pravastatin. Jpn J Pharmacol.. 1996;70:149-156.[Medline] [Order article via Infotrieve]
34.
Carew TE, Pittman RC, Marchand ER, Steinberg D.
Measurement in vivo of irreversible degradation of low density
lipoprotein in the rabbit aorta: predominance of intimal
degradation. Arteriosclerosis.. 1984;4:214-224.
35.
Williams JK, Adams MR, Klopfenstein HS. Estrogen
modulates responses of atherosclerotic coronary
arteries. Circulation.. 1990;81:1680-1687.
36.
Hayashi T, Fukoto JM, Ignarro LJ, Chaudhuri G.
Basal release of nitric oxide from aortic rings is greater in
female rabbits than in male rabbits: implications for
atherosclerosis. Proc Natl Acad Sci
U S A.. 1992;89:11259-11263.
37.
Kauser K, Rubanyi GM. Gender difference in
bioassayable endothelium-derived nitric oxide from
isolated rat aortae. Am J Physiol.. 1994;267:H2311H2317.
38.
Losordo DW, Kearney M, Kim EA, Jekanowski J, Isner JM.
Variable expression of the estrogen receptor in normal and
atherosclerotic coronary arteries of premenopausal
women. Circulation.. 1994;89:1501-1510.
39. Paigen B, Holmes PA, Mitchell D, Albee D. Comparison of atherosclerotic lesions and HDL-lipid levels in male, female and testosterone-treated female mice from steroid C57BL/b, BALB/c, and C34. Atherosclerosis.. 1987;64:215-221.[Medline] [Order article via Infotrieve]
40. Rubanyi BM, Freat AD, Kauser K, Sukovich D, Burton G, Lubahn DB, Couse JF, Curtis SW, Korach KS. Vascular estrogen receptors and endothelium-derived nitric oxide production in the mouse aorta. J Clin Invest.. 1997;99:2429-2437.[Medline] [Order article via Infotrieve]
This article has been cited by other articles:
![]() |
J. R. Durrant, D. R. Seals, M. L. Connell, M. J. Russell, B. R. Lawson, B. J. Folian, A. J. Donato, and L. A. Lesniewski Voluntary wheel running restores endothelial function in conduit arteries of old mice: direct evidence for reduced oxidative stress, increased superoxide dismutase activity and down-regulation of NADPH oxidase J. Physiol., July 1, 2009; 587(13): 3271 - 3285. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. B. Anea, M. Zhang, D. W. Stepp, G. B. Simkins, G. Reed, D. J. Fulton, and R. D. Rudic Vascular Disease in Mice With a Dysfunctional Circadian Clock Circulation, March 24, 2009; 119(11): 1510 - 1517. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. W. Nuno, V. P. Korovkina, S. K. England, and K. G. Lamping RhoA Activation Contributes to Sex Differences in Vascular Contractions Arterioscler. Thromb. Vasc. Biol., September 1, 2007; 27(9): 1934 - 1940. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. A. Stapleton, Adam. G. Goodwill, M. E. James, and J. C. Frisbee Altered mechanisms of endothelium-dependent dilation in skeletal muscle arterioles with genetic hypercholesterolemia Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2007; 293(3): R1110 - R1119. [Abstract] [Full Text] [PDF] |
||||
![]() |
V. A. Korshunov, S. M. Schwartz, and B. C. Berk Vascular Remodeling: Hemodynamic and Biochemical Mechanisms Underlying Glagov's Phenomenon Arterioscler. Thromb. Vasc. Biol., August 1, 2007; 27(8): 1722 - 1728. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Kitayama, F. M. Faraci, S. R. Lentz, and D. D. Heistad Cerebral Vascular Dysfunction During Hypercholesterolemia Stroke, July 1, 2007; 38(7): 2136 - 2141. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Rahmani, R. P. Cruz, D. J. Granville, and B. M. McManus Allograft Vasculopathy Versus Atherosclerosis Circ. Res., October 13, 2006; 99(8): 801 - 815. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Ohashi, M. S. Runge, F. M. Faraci, and D. D. Heistad MnSOD Deficiency Increases Endothelial Dysfunction in ApoE-Deficient Mice Arterioscler. Thromb. Vasc. Biol., October 1, 2006; 26(10): 2331 - 2336. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. Lorkowska, M. Bartus, M. Franczyk, R. B. Kostogrys, J. Jawien, P. M. Pisulewski, and S. Chlopicki Hypercholesterolemia Does Not Alter Endothelial Function in Spontaneously Hypertensive Rats J. Pharmacol. Exp. Ther., June 1, 2006; 317(3): 1019 - 1026. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. Gigante, G. Morlino, M. T. Gentile, M. G. Persico, and S. De Falco Plgf-/-eNos-/- mice show defective angiogenesis associated with increased oxidative stress in response to tissue ischemia FASEB J, May 1, 2006; 20(7): 970 - 972. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. Godfraind Antioxidant effects and the therapeutic mode of action of calcium channel blockers in hypertension and atherosclerosis Phil Trans R Soc B, December 29, 2005; 360(1464): 2259 - 2272. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Kyselovic, P. Martinka, Z. Batova, A. Gazova, and T. Godfraind Calcium Channel Blocker Inhibits Western-Type Diet-Evoked Atherosclerosis Development in ApoE-Deficient Mice J. Pharmacol. Exp. Ther., October 1, 2005; 315(1): 320 - 328. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. G. Lamping, J. Wess, Y. Cui, D. W. Nuno, and F. M. Faraci Muscarinic (M) Receptors in Coronary Circulation: Gene-Targeted Mice Define the Role of M2 and M3 Receptors in Response to Acetylcholine Arterioscler. Thromb. Vasc. Biol., July 1, 2004; 24(7): 1253 - 1258. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. G. Frank, S. E. Woodman, D. S. Park, and M. P. Lisanti Caveolin, Caveolae, and Endothelial Cell Function Arterioscler. Thromb. Vasc. Biol., July 1, 2003; 23(7): 1161 - 1168. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. M. Crauwels, C. E. Van Hove, P. Holvoet, A. G. Herman, and H. Bult Plaque-associated endothelial dysfunction in apolipoprotein E-deficient mice on a regular diet. Effect of human apolipoprotein AI Cardiovasc Res, July 1, 2003; 59(1): 189 - 199. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Pelat, C. Dessy, P. Massion, J.-P. Desager, O. Feron, and J.-L. Balligand Rosuvastatin Decreases Caveolin-1 and Improves Nitric Oxide-Dependent Heart Rate and Blood Pressure Variability in Apolipoprotein E-/- Mice In Vivo Circulation, May 20, 2003; 107(19): 2480 - 2486. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. de Nigris, L. O. Lerman, S. W. Ignarro, G. Sica, A. Lerman, W. Palinski, L. J. Ignarro, and C. Napoli From the Cover: Beneficial effects of antioxidants and L-arginine on oxidation-sensitive gene expression and endothelial NO synthase activity at sites of disturbed shear stress PNAS, February 4, 2003; 100(3): 1420 - 1425. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Gervais, S. Pons, A. Nicoletti, C. Cosson, J.-F. Giudicelli, and C. Richer Fluvastatin Prevents Renal Dysfunction and Vascular NO Deficit in Apolipoprotein E-Deficient Mice Arterioscler. Thromb. Vasc. Biol., February 1, 2003; 23(2): 183 - 189. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. F. Bentzon, G. Pasterkamp, and E. Falk Expansive Remodeling Is a Response of the Plaque-Related Vessel Wall in Aortic Roots of ApoE-Deficient Mice: An Experiment of Nature Arterioscler. Thromb. Vasc. Biol., February 1, 2003; 23(2): 257 - 262. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. P. Didion, M. J. Ryan, L. A. Didion, P. E. Fegan, C. D. Sigmund, and F. M. Faraci Increased Superoxide and Vascular Dysfunction in CuZnSOD-Deficient Mice Circ. Res., November 15, 2002; 91(10): 938 - 944. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. P. Didion, M. J. Ryan, G. L. Baumbach, C. D. Sigmund, and F. M. Faraci Superoxide contributes to vascular dysfunction in mice that express human renin and angiotensinogen Am J Physiol Heart Circ Physiol, October 1, 2002; 283(4): H1569 - H1576. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y. Chu, D. D. Heistad, K. L. Knudtson, K. G. Lamping, and F. M. Faraci Quantification of mRNA for Endothelial NO Synthase in Mouse Blood Vessels by Real-Time Polymerase Chain Reaction Arterioscler. Thromb. Vasc. Biol., April 1, 2002; 22(4): 611 - 616. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. V d'Uscio, M. Barton, S. Shaw, and T. F Luscher Chronic ETA receptor blockade prevents endothelial dysfunction of small arteries in apolipoprotein E-deficient mice Cardiovasc Res, February 1, 2002; 53(2): 487 - 495. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. J. Ryan, S. P. Didion, D. R. Davis, F. M. Faraci, and C. D. Sigmund Endothelial Dysfunction and Blood Pressure Variability in Selected Inbred Mouse Strains Arterioscler. Thromb. Vasc. Biol., January 1, 2002; 22(1): 42 - 48. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Godecke, M. Ziegler, Z. Ding, and J. Schrader Endothelial dysfunction of coronary resistance vessels in apoE-/- mice involves NO but not prostacyclin-dependent mechanisms Cardiovasc Res, January 1, 2002; 53(1): 253 - 262. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. V. d'Uscio, L. A. Smith, and Z. S. Katusic Hypercholesterolemia Impairs Endothelium-Dependent Relaxations in Common Carotid Arteries of Apolipoprotein E-Deficient Mice Stroke, November 1, 2001; 32(11): 2658 - 2664. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. Lutgens, E. D. de Muinck, S. Heeneman, and M. J.A.P. Daemen Compensatory Enlargement and Stenosis Develop in ApoE-/- and ApoE*3-Leiden Transgenic Mice Arterioscler. Thromb. Vasc. Biol., August 1, 2001; 21(8): 1359 - 1365. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. V. d'Uscio, T. A. Baker, C. B. Mantilla, L. Smith, D. Weiler, G. C. Sieck, and Z. S. Katusic Mechanism of Endothelial Dysfunction in Apolipoprotein E-Deficient Mice Arterioscler. Thromb. Vasc. Biol., June 1, 2001; 21(6): 1017 - 1022. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. Darblade, D. Caillaud, M. Poirot, M.-J. Fouque, J.-C. Thiers, J. Rami, F. Bayard, and J.-F. Arnal Alteration of plasmalemmal caveolae mimics endothelial dysfunction observed in atheromatous rabbit aorta Cardiovasc Res, June 1, 2001; 50(3): 566 - 576. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. J. Hartley, A. K. Reddy, S. Madala, B. Martin-McNulty, R. Vergona, M. E. Sullivan, M. Halks-Miller, G. E. Taffet, L. H. Michael, M. L. Entman, et al. Hemodynamic changes in apolipoprotein E-knockout mice Am J Physiol Heart Circ Physiol, November 1, 2000; 279(5): H2326 - H2334. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. G. Lamping, D. W. Nuno, E. G. Shesely, N. Maeda, and F. M. Faraci Vasodilator mechanisms in the coronary circulation of endothelial nitric oxide synthase-deficient mice Am J Physiol Heart Circ Physiol, October 1, 2000; 279(4): H1906 - H1912. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. R. Lentz, R. A. Erger, S. Dayal, N. Maeda, M. R. Malinow, D. D. Heistad, and F. M. Faraci Folate dependence of hyperhomocysteinemia and vascular dysfunction in cystathionine beta -synthase-deficient mice Am J Physiol Heart Circ Physiol, September 1, 2000; 279(3): H970 - H975. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. Liuba, P. Karnani, E. Pesonen, I. Paakkari, A. Forslid, L. Johansson, K. Persson, T. Wadstrom, and R. Laurini Endothelial Dysfunction After Repeated Chlamydia pneumoniae Infection in Apolipoprotein E-Knockout Mice Circulation, August 29, 2000; 102(9): 1039 - 1044. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. Kauser, V. da Cunha, R. Fitch, C. Mallari, and G. M. Rubanyi Role of endogenous nitric oxide in progression of atherosclerosis in apolipoprotein E-deficient mice Am J Physiol Heart Circ Physiol, May 1, 2000; 278(5): H1679 - H1685. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. J. Williams, R. Scalia, K. D. Mazany, W. V. Rodrigueza, and A. M. Lefer Rapid Restoration of Normal Endothelial Functions in Genetically Hyperlipidemic Mice by a Synthetic Mediator of Reverse Lipid Transport Arterioscler. Thromb. Vasc. Biol., April 1, 2000; 20(4): 1033 - 1039. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Hamasaki, S. T. Higano, J. A. Suwaidi, R. A. Nishimura, K. Miyauchi, D. R. Holmes Jr, and A. Lerman Cholesterol-Lowering Treatment Is Associated With Improvement in Coronary Vascular Remodeling and Endothelial Function in Patients With Normal or Mildly Diseased Coronary Arteries Arterioscler. Thromb. Vasc. Biol., March 1, 2000; 20(3): 737 - 743. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. P. Didion, C. D. Sigmund, F. M. Faraci, and Z. S. Katusic Impaired Endothelial Function in Transgenic Mice Expressing Both Human Renin and Human Angiotensinogen • Editorial Comment Stroke, March 1, 2000; 31(3): 760 - 765. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. M. Faraci and C. D. Sigmund Vascular Biology in Genetically Altered Mice : Smaller Vessels, Bigger Insight Circ. Res., December 3, 1999; 85(12): 1214 - 1225. [Full Text] [PDF] |
||||
![]() |
R. Yang, L. Powell-Braxton, A. K. Ogaoawara, N. Dybdal, S. Bunting, O. Ohneda, and H. Jin Hypertension and Endothelial Dysfunction in Apolipoprotein E Knockout Mice Arterioscler. Thromb. Vasc. Biol., November 1, 1999; 19(11): 2762 - 2768. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. A. Gunnett, D. J. Berg, F. M. Faraci, and G. Feuerstein Vascular Effects of Lipopolysaccharide Are Enhanced in Interleukin-10-Deficient Mice • Editorial Comment Stroke, October 1, 1999; 30(10): 2191 - 2196. [Abstract] [Full Text] [PDF] |
||||
![]() |
N. de las Heras, P. Aragoncillo, R. Maeso, S. Vazquez-Perez, J. Navarro-Cid, M. DeGasparo, J. Mann, L. M. Ruilope, V. Cachofeiro, and V. Lahera AT1 Receptor Antagonism Reduces Endothelial Dysfunction and Intimal Thickening in Atherosclerotic Rabbits Hypertension, October 1, 1999; 34(4): 969 - 975. [Abstract] [Full Text] [PDF] |
||||
![]() |
V. Deckert, G. Lizard, N. Duverger, A. Athias, V. Palleau, F. Emmanuel, M. Moisant, P. Gambert, C. Lallemant, and L. Lagrost Impairment of Endothelium-Dependent Arterial Relaxation By High-Fat Feeding in ApoE-Deficient Mice : Toward Normalization By Human ApoA-I Expression Circulation, September 14, 1999; 100(11): 1230 - 1235. [Abstract] [Full Text] [PDF] |
||||
![]() |
G. Caligiuri, B. Levy, J. Pernow, P. Thoren, and G. K. Hansson Myocardial infarction mediated by endothelin receptor signaling in hypercholesterolemic mice PNAS, June 8, 1999; 96(12): 6920 - 6924. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. G. Lamping, D. W. Nuno, D. A. Chappell, and F. M. Faraci Agonist-specific impairment of coronary vascular function in genetically altered, hyperlipidemic mice Am J Physiol Regulatory Integrative Comp Physiol, April 1, 1999; 276(4): R1023 - R1029. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Barton, C. C. Haudenschild, L. V. d'Uscio, S. Shaw, K. Munter, and T. F. Luscher Endothelin ETA receptor blockade restores NO-mediated endothelial function and inhibits atherosclerosis in apolipoprotein E-deficient mice PNAS, November 24, 1998; 95(24): 14367 - 14372. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. A. Gunnett, Y. Chu, D. D. Heistad, A. Loihl, and F. M. Faraci Vascular effects of LPS in mice deficient in expression of the gene for inducible nitric oxide synthase Am J Physiol Heart Circ Physiol, August 1, 1998; 275(2): H416 - H421. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. Carmeliet, L. Moons, and D. Collen Mouse models of angiogenesis, arterial stenosis, atherosclerosis and hemostasis Cardiovasc Res, July 1, 1998; 39(1): 8 - 33. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. M. Faraci, C. D. Sigmund, E. G. Shesely, N. Maeda, and D. D. Heistad Responses of carotid artery in mice deficient in expression of the gene for endothelial NO synthase Am J Physiol Heart Circ Physiol, February 1, 1998; 274(2): H564 - H570. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Dayal, T. Bottiglieri, E. Arning, N. Maeda, M. R. Malinow, C. D. Sigmund, D. D. Heistad, F. M. Faraci, and S. R. Lentz Endothelial Dysfunction and Elevation of S-Adenosylhomocysteine in Cystathionine {beta}-Synthase-Deficient Mice Circ. Res., June 8, 2001; 88(11): 1203 - 1209. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y. Chu, D. D. Heistad, K. L. Knudtson, K. G. Lamping, and F. M. Faraci Quantification of mRNA for Endothelial NO Synthase in Mouse Blood Vessels by Real-Time Polymerase Chain Reaction Arterioscler. Thromb. Vasc. Biol., April 1, 2002; 22(4): 611 - 616. [Abstract] [Full Text] [PDF] |
||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
ATVB Home | Subscriptions | Archives | Feedback | Authors | Help | AHA Journals Home | Search Copyright © 1997 American Heart Association, Inc. All rights reserved. Unauthorized use prohibited. |