This Article Abstract Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Bagi, Z. Articles by Koller, A. Search for Related Content PubMed PubMed Citation Articles by Bagi, Z. Articles by Koller, A. Related Collections Animal models of human disease Pathophysiology Other arteriosclerosis Peripheral vascular disease Endothelium/vascular type/nitric oxide

(Arteriosclerosis, Thrombosis, and Vascular Biology. 2001;21:233.)
© 2001 American Heart Association, Inc.

Vascular Biology

Flow-Induced Constriction in Arterioles of Hyperhomocysteinemic Rats Is Due to Impaired Nitric Oxide and Enhanced Thromboxane A₂ Mediation

Zsolt Bagi; Zoltan Ungvari; Lajos Szollár; Akos Koller

From the Department of Pathophysiology, Semmelweis University, Budapest, Hungary (Z.B., Z.U., L.S., A.K.); and Department of Physiology, New York Medical College, Valhalla, NY (A.K.).

Correspondence to Akos Koller, MD, PhD, Department of Physiology, New York Medical College, Valhalla, NY 10595. E-mail koller{at}nymc.edu

	Abstract

Top Abstract Introduction Methods Results Discussion References

 
Abstract—Hyperhomocysteinemia (HHcy) is thought to promote arteriosclerosis and peripheral arterial disease, in part by impairing the function of endothelium. Because flow-induced dilation is mediated by the endothelium, we hypothesized that HHcy alters this response by interfering with the synthesis/action of NO and prostaglandins. Thus, changes in the diameter of isolated, pressurized (at 80 mm Hg) gracilis skeletal muscle arterioles (diameter 170 µm) from control and methionine diet–induced HHcy rats were investigated with videomicroscopy. Increases in intraluminal flow (from 0 to 25 µL/min) resulted in dilations of control arterioles (maximum, 34±4 µm). In contrast, increases in flow elicited constrictions of HHcy arterioles (-36±3 µm). In control arterioles, the NO synthase inhibitor N-nitro-L-arginine-methyl ester significantly attenuated (50%) dilation, whereas the additional administration of indomethacin, an inhibitor of cyclooxygenase, eliminated flow-induced dilation. In the arterioles of HHcy rats, flow-induced constriction was not affected by N-nitro-L-arginine-methyl ester, whereas it was abolished by indomethacin or the prostaglandin H₂/thromboxane A₂ (TXA₂) receptor antagonist SQ 29,548 or the TXA₂ synthase inhibitor CGS 13,080. Thus, in HHcy, increases in intraluminal flow elicit constrictions of skeletal muscle arterioles due to the impaired NO and enhanced TXA₂ mediation of the response, alterations that likely contribute to the development of peripheral arterial disease.

Key Words: homocysteine • arteriole • flow-induced response • endothelium • nitric oxide • thromboxane A₂

	Introduction

Top Abstract Introduction Methods Results Discussion References

 
Increasing epidemiological and experimental evidence suggests that an elevated plasma level of homocysteine is associated with the development of peripheral arterial disease.^{1 2 3 4 5} Homocysteine is a sulfur-containing amino acid that is formed during the metabolism of the essential amino acid methionine.⁴ Plasma homocysteine concentration can be increased through alterations in genetic and nutritional factors, such as various enzyme (cystathione-ß-synthase, methyltetrahydrofolate reductase) abnormalities and deficiency of vitamins (folic acid, cyanocobalamin, pyridoxal phosphate), all of which participate in the metabolism of homocysteine and methionine (for further references, see Lentz et al⁴ ). Previously, several mechanisms have been suggested by which elevated homocysteine levels promote peripheral arterial disease, such as vascular smooth muscle proliferation,⁶ platelet activation,⁷ and endothelial injury.⁷

It is likely that hyperhomocysteinemia (HHcy) impairs the vasoactive function of the endothelium of arteries and arterioles before the development of morphological changes.^{8 9 10 11} Indeed, the diminished increase in hindlimb circulation to acetylcholine in monkeys with diet-induced HHcy^{8 9} suggests that the dilator capacity of small arteries and arterioles responsible for tissue vascular resistance is altered by HHcy. Also, we recently demonstrated that endothelium-dependent acetylcholine- and histamine-induced NO-mediated dilations are impaired in isolated skeletal muscle arterioles of HHcy rats.¹⁰ In addition, bradykinin elicits an enhanced constriction of arterioles of HHcy rats due to the augmented release of thromboxane A₂ (TXA₂) from the endothelium.¹¹ Moreover, in the same HHcy rats, we found an enhanced platelet aggregation that could be inhibited by blocking TXA₂ receptors. These findings suggest that the agonist-induced synthesis of NO and prostaglandins by the resistance vessels is altered in HHcy.

One of the primary in vivo stimuli for the endothelial synthesis/release of NO and prostaglandins in arterioles is an increase in intraluminal flow.¹² This mechanism is important because unlike the responses to acetylcholine and bradykinin, it is known to be involved in the moment-to-moment regulation of arteriolar diameter in vivo.¹³ On the basis of the aforementioned studies, it is logical to hypothesize that flow-induced arteriolar dilation is altered in HHcy rats. Thus, in the present study we sought to investigate the responses of isolated gracilis muscle arterioles of rats with HHcy^{10 11 14 15} to increases in intraluminal flow, to contrast the responses to those of rats with normal plasma homocysteine levels, and to characterize the alterations in the mediation of responses by endothelial factors.

	Methods

Top Abstract Introduction Methods Results Discussion References

 
In male Wistar rats (weight 325 to 345 g; purchased from Charles River Co), moderate HHcy was induced by the administration of L-methionine (1 g · kg body wt^-1 · d^-1) in the drinking water for a period of 4 weeks (n=35), as described previously.^{8 9 10 11} The doses administered were based on average daily fluid intake. This diet is known to increase plasma total homocysteine levels in rats from 6 to 21 µmol/L.^{10 11} The water consumption and body weight did not differ significantly between methionine-fed rats and age-matched control rats (n=35).

Isolation of Arterioles
Experiments were conducted on isolated arterioles (inside diameter 170 µm) of rat gracilis muscle as described previously.^{10 11} Briefly, on the fourth week after overnight fasting, rats were anesthetized with an intraperitoneal injection of sodium pentobarbital (50 mg/kg). The gracilis muscle was dissected and placed in a silicone-lined Petri dish containing cold (0° to 4°C) physiological salt solution (PSS) composed of (in mmol/L) NaCl 110, KCl 5.0, CaCl₂ 2.5, MgSO₄ 1.0, KH₂PO₄ 1.0, dextrose 10.0, and NaHCO₃ 24.0 and was equilibrated with a gas mixture of 10% O₂ and 5% CO₂, balanced with nitrogen, at pH 7.4. With microsurgery instruments and an operating microscope, a segment of 1.5 mm in length of an arteriole running intramuscularly was isolated and transferred into an organ chamber containing 2 glass micropipettes filled with PSS. From a reservoir, the vessel chamber (15 mL) was continuously supplied with PSS at a rate of 20 mL/min. After the vessel had been mounted on the proximal (inflow) pipette and was secured with sutures, the perfusion pressure was raised to 20 mm Hg to clear the lumen. Then the other end of the vessel was mounted on the distal (outflow) pipette.¹⁶ Both micropipettes were connected with silicone tubing to an adjustable PSS reservoir. Inflow and outflow pressures were measured with an electromanometer. The intraluminal pressure was slowly increased to 80 mm Hg. The temperature was set at 37°C by a temperature controller (Grant Instruments), and the vessel was allowed to develop spontaneous tone in response to intraluminal pressure under no-flow conditions (equilibration period 1 hour). The inner arteriolar diameter was measured with videomicroscopy with a microangiometer and recorded on a chart recorder. Perfusate flow was measured with a ball flowmeter (Omega Engineering Inc).

Experimental Protocols
Changes in the diameter of arterioles were assessed in response to step increases in intraluminal flow (from 0 to 25 µL/min). Flow was established at a constant intravascular pressure (80 mm Hg) by changing the inflow and outflow pressures to an equal degree, but in opposite directions, to keep midpoint luminal pressure constant.¹⁶ Arterioles were then incubated with 10^-4 mol/L N-nitro-L-arginine-methyl ester (L-NAME), an inhibitor of NO synthesis, for 20 minutes under zero-flow conditions, and flow-induced responses were reassessed. In the presence of L-NAME, arterioles were also incubated with the cyclooxygenase inhibitor indomethacin (10^-5 mol/L) for 20 minutes under zero-flow conditions, and then flow-induced responses were obtained again. In separate experiments, we assessed flow-induced arteriolar responses before and after indomethacin.

In other experiments, flow-induced arteriolar responses were assessed in the absence and the presence of the prostaglandin (PG)H₂/TXA₂ receptor inhibitor SQ 29,548 (10^-6 mol/L) or the TXA₂ synthase inhibitor CGS 13,080 (5x10^-6 mol/L, 20-minute incubation).¹⁷ Responses of control and HHcy arterioles to increases in flow were also obtained after endothelium removal. The endothelium of the arterioles was removed through perfusion of the vessel with air, as described previously.¹⁰

At the conclusion of each experiment to obtain the maximum passive diameter, the suffusion solution was changed to a Ca²⁺-free PSS that contained EGTA (10^-3 mol/L), and the vessel was incubated for 10 minutes. All drugs were added to the vessel chamber, and final concentrations are reported. All salts and chemicals were obtained from Sigma-Aldrich Co. Solutions were prepared on the day of the experiment. Data are expressed as mean±SEM Statistical analyses were performed by 2-way ANOVA for repeated measures, followed by the Tukey post hoc test or Student’s t test, as appropriate. P<0.05 was considered statistically significant.

	Results

Top Abstract Introduction Methods Results Discussion References

 
Arterioles isolated from the gracilis muscle of control and HHcy rats developed active tone in response to intraluminal pressure of 80 mm Hg without the use of a vasoactive agent (control 166±8 µm, HHcy 174±12 µm, NS). The passive diameters of control and HHcy arterioles in the absence of extracellular Ca²⁺ were 226±6 and 236±9 µm (NS), respectively (at 80 mm Hg).

Stepwise increases in intraluminal flow elicited significant dilation in arterioles of the control rats, whereas increases in flow constricted arterioles of the HHcy rats (Figure 1.). Removal of the endothelium completely abolished both types of flow-induced arteriolar responses (Figure 1.).

View larger version (22K): [in this window] [in a new window]   Figure 1. Changes in diameter of skeletal muscle arterioles isolated from control (n=35) and HHcy rats (n=35) as a function of intraluminal flow in the presence and absence of the endothelium (-Endo). Data are mean±SEM. *Significant difference (P<0.05).

Inhibition of NO synthesis with L-NAME significantly reduced (by 50%) flow-induced dilation in control arterioles (Figure 2A). When indomethacin was administered in the superfusate in addition to L-NAME, flow-induced dilation was completely abolished in the control arterioles (Figure 2A). Flow-induced constriction in HHcy arterioles was not significantly affected by inhibition of NO synthesis, whereas it was completely abolished in the presence of indomethacin with or without L-NAME (Figure 2B).

View larger version (22K): [in this window] [in a new window]   Figure 2. Changes in diameter of skeletal muscle arterioles isolated from control (n=15; A) and HHcy (n=15; B) rats as a function of perfusate flow in the presence of the NO synthase inhibitor L-NAME (10-4 mol/L), the cyclooxygenase inhibitor indomethacin (Indo; 10-5 mol/L), or both. Data are mean±SEM. *Significant difference (P<0.05).

The PGH₂/TXA₂ receptor antagonist SQ 29,548 had no effect on flow-induced dilation in the control arterioles, whereas it completely abolished flow-induced constriction of the HHcy arterioles (Figure 3A). The TXA₂ synthase inhibitor CGS 13,080 had no effect on flow-induced dilation in control arterioles, whereas it abolished the flow-induced constriction of HHcy arterioles (Figure 3B). L-NAME, indomethacin, SQ 29,548, or CGS 13,080 had no significant effect on the basal arteriolar diameter of control and HHcy rats (Table).

View larger version (22K): [in this window] [in a new window]   Figure 3. Changes in diameter of skeletal muscle arterioles isolated from control (n=15) and HHcy (n=15) rats as a function of perfusate flow in the absence and presence of the PGH2/TXA2 receptor antagonist SQ29,548 (10-6 mol/L, A) or the TXA2 synthase inhibitor CGS 13,080 (5x10-6 mol/L, B). Data are mean±SEM. *Significant difference (P<0.05).

View this table: [in this window] [in a new window]   Table 1. Effects of Enzyme Inhibitors and Receptor Blocker on Basal Diameter of Arterioles

	Discussion

Top Abstract Introduction Methods Results Discussion References

 
The salient findings of the present study are that increases in intraluminal flow resulted in the constriction of arterioles isolated from rats with an elevated plasma homocysteine concentration. The constrictions were not affected by inhibition of NO synthesis but were abolished by inhibition of prostaglandin synthesis, PGH₂/TXA₂ receptors, or TXA₂ synthase. In contrast, arterioles from rats fed a normal diet dilated in response to increases in flow, a response that is mediated by NO and dilator prostaglandins.

Our previous studies showed that plasma homocysteine concentrations in rats fed a methionine diet are increased by 3-fold,^{10 11} reaching a concentration similar to that shown to be associated with an increased risk of vascular disease in humans.^{1 4 5 18} In these studies, we demonstrated that acetylcholine and histamine–induced, NO-mediated endothelial dilations are reduced in skeletal muscle arterioles of HHcy rats.¹⁰ In addition, bradykinin induces an enhanced constriction of HHcy arterioles via increased TXA₂ production in the endothelium.¹¹ Also, it has been reported that elevated plasma homocysteine concentrations are associated with an impaired dilation of conduit arteries in response to the release of an occlusion in humans.^{19 20 21 22 23 24 25} Together with previous findings regarding large vessels,^{8 9} these studies suggest that HHcy importantly alters the endothelial regulation of arterial and arteriolar tone, which is primarily responsible for the determination of tissue blood supply.

In the present study, we sought to investigate the flow-induced response of arterioles isolated from HHcy rats because it is known that increases in intraluminal flow stimulate the endothelium to release vasoactive mediators¹³ and because the flow-sensitive mechanism is important in the moment-to-moment regulation of peripheral vascular resistance. First, we confirmed that increases in intraluminal flow elicit substantial endothelium-dependent dilations in arterioles of control rats²⁶ (Figure 1.). In contrast, in arterioles isolated from HHcy rats, increases in intraluminal flow elicited significant constrictions in the presence of the endothelium (Figure 1.). In the absence of the endothelium, both responses were abolished. In control arterioles, flow-induced dilation is mediated by NO and dilator prostaglandins because the inhibition of NO synthesis significantly reduced the response, whereas additional inhibition of the prostaglandin synthesis abolished this response (Figure 2A), confirming our previous findings.²⁷ In contrast, inhibition of NO synthesis did not affect flow-induced constriction in arterioles of the HHcy rats (Figure 2B). These alterations are likely due to impaired endothelial synthesis or bioavailability of NO rather than to altered dilatory capacity of the smooth muscle, because arteriolar dilations in response to the endothelium-independent NO donor sodium nitroprusside are not affected by HHcy.¹⁰

The finding that indomethacin (Figure 2B) or the PGH₂/TXA₂ receptor antagonist SQ 29,548 (Figure 3A) abolished flow-induced constrictions of HHcy arterioles indicates that increases in flow activate the arachidonic acid cascade in the endothelium; however, predominantly constrictor (PGH₂/TXA₂) instead of dilator prostaglandins are released. Because the TXA₂ synthase inhibitor CGS 13,080 also abolished flow-induced constrictions, it seems that TXA₂ is synthesized (and released) in HHcy in response to flow (Figure 3B). These results are in accordance with recent data that show methionine load–induced HHcy acutely increases TXA₂ synthesis in rats²⁸ and with our recent findings that demonstrate enhanced TXA₂ production in the endothelium of HHcy arterioles in response to bradykinin.¹¹ Vascular endothelium represents a large surface that is continuously exposed to changes in blood flow. Thus, it is likely that the flow-induced arteriolar release of TXA₂ together with that released from platelets¹¹ contributes to the development of increased vascular tone and urinary excretion of TXB₂, the stable end metabolite of TXA₂ shown to be present in patients with genetic HHcy.^{29 30}

The underlying mechanism for the simultaneous impaired NO release and enhanced TXA₂ production in the endothelium of arterioles of HHcy rats^{10 11} is not known. Several previous studies in endothelial cells in culture^{31 32} suggest a role for an increased level of reactive oxygen species (ROS). Because endothelial cells have a limited capacity to metabolize homocysteine, they are particularly vulnerable to elevated levels of homocysteine.³³ Homocysteine is thought to promote the generation of ROS via the auto-oxidation of the sulfhydryl group³¹ or by decreasing the intracellular levels of glutathione and glutathione peroxidase that are involved in the elimination of free radicals.^{32 34 35} Enhanced levels of ROS can interfere with NO and reduce the release of NO in response to increases in flow and agonists in HHcy. Indeed, recent studies showed that in humans after methionine loading, impaired brachial artery dilations in response to acetylcholine and to the release of forearm occlusion are restored with the antioxidant ascorbic acid.¹⁹ The presence of ROS may also favor the formation of TXA₂, in part through an increased formation of arachidonic acid.^{11 28} Also, it is possible that superoxide can form peroxynitrite with NO, which then may inhibit PGI₂ synthase and result in an enhanced formation of constrictor prostaglandins,³⁶ especially when the level of arachidonic acid is elevated. Interestingly, the simultaneous impairment of NO mediation of arteriolar responses and an enhanced synthesis of constrictor prostaglandins also has been shown in hypertension³⁷ and diabetes mellitus,³⁸ diseases that are also thought to be associated with an increased formation of ROS,^{16 38} suggesting a common mechanism of action for the development of endothelial dysfunction.

It is likely that these changes in the vasoactive function of arteriolar endothelium represent early effects of HHcy and that they precede structural changes in the vascular wall.⁶ By adjusting the diameter, a flow-dependent mechanism plays an important role in the dilation of precapillary vessels during increased demand, such as exercise.²⁶ It is thought that flow-dependent dilation amplifies increases in blood flow to working skeletal muscle to prevent the development of relative oxygen deficiency and an increase in wall shear stress.³⁹ In HHcy, flow-induced constriction of the arterioles may limit tissue blood supply, whereas the impaired of NO release and upregulated synthesis of TXA₂ in the endothelium, together with the simultaneously increased TXA₂ synthesis in platelets,^{11 28} can substantially enhance platelet aggregation as well, favoring thrombus formation and leading to occlusive peripheral vascular disease, such as intermittent claudication.^{2 3 40}

In conclusion, the present study is the first to demonstrate that flow-dependent arteriolar dilation observed under normal healthy conditions is converted to constriction in HHcy rats. The constriction is due to the simultaneously impaired NO and enhanced TXA₂ mediation of arteriolar responses to increases in flow. Such alterations in the vasoactive function of endothelium in HHcy could limit or reduce tissue perfusion, thereby promoting symptomatic peripheral arterial disease.

	Acknowledgments

 
This work was supported by grants from the Hungarian National Science Research Foundation (OTKA T-034779 and T-033117), the National Heart, Lung, and Blood Institute of the National Institutes of Health (HL-46813 and HL-43023), and the American Heart Association (50849T).

Received November 1, 2000; accepted November 22, 2000.

	References

Top Abstract Introduction Methods Results Discussion References

 
1. Malinow MR, Kang SS, Taylor LM, Wong PW, Coull B, Inahara T, Mukerjee D, Sexton G, Upson B. Prevalence of hyperhomocyst(e)inemia in patients with peripheral arterial occlusive disease. Circulation. 1989;79:1180–1188.[Abstract/Free Full Text]

2. Molgaard J, Malinow MR, Lassvik C, Holm AC, Upson B, Olsson AG. Hyperhomocyst(e)inaemia: an independent risk factor for intermittent claudication. J Intern Med. 1992;231:273–279.[Medline] [Order article via Infotrieve]

3. Taylor LM Jr, Moneta GL, Sexton GJ, Schuff RA, Porter JM. Prospective blinded study of the relationship between plasma homocysteine and progression of symptomatic peripheral arterial disease. J Vasc Surg. 1999;29:8–19.[Medline] [Order article via Infotrieve]

4. Ueland PM, Refsum H. Plasma homocysteine, a risk factor for vascular disease: plasma levels in health, disease, and drug therapy. J Lab Clin Med. 1989;114:473–501.[Medline] [Order article via Infotrieve]

5. Clarke R, Daly L, Robinson K, Naughten E, Cahalane S, Fowler B, Graham I, Hyperhomocysteinemia: an independent risk factor for vascular disease. N Engl J Med. 1991;324:1149–1155.[Abstract]

6. McCully KS. Vascular pathology of homocysteinemia: implications for the pathogenesis of arteriosclerosis. Am J Pathol. 1969;56:111–128.[Medline] [Order article via Infotrieve]

7. Harker LA, Ross R, Slichter SJ, Scott CR. Homocystine-induced arteriosclerosis: the role of endothelial cell injury and platelet response in its genesis. J Clin Invest. 1976;58:731–741.

8. Lentz SR, Sobey CG, Piegors DJ, Bhopatkar MY, Faraci FM, Malinow MR, Heistad DD. Vascular dysfunction in monkeys with diet-induced hyperhomocyst(e)inemia. J Clin Invest. 1996;98:24–29.[Medline] [Order article via Infotrieve]

9. Lentz SR, Malinow MR, Piegors DJ, Bhopatkar-Teredesai M, Faraci FM, Heistad DD. Consequences of hyperhomocyst(e)inemia on vascular function in atherosclerotic monkeys. Arterioscler Thromb Vasc Biol. 1997;17:2930–2934.[Abstract/Free Full Text]

10. Ungvari Z, Pacher P, Rischak K, Szollar L, Koller A. Dysfunction of nitric oxide mediation in isolated rat arterioles with methionine diet-induced hyperhomocysteinemia. Arterioscler Thromb Vasc Biol. 1999;19:1899–1904.[Abstract/Free Full Text]

11. Ungvari Z, Sarkadi-Nagy E, Bagi Z, Szollar L, Koller A. Simultaneously increased TXA₂ activity in isolated arterioles and platelets of rats with hyperhomocysteinemia. Arterioscler Thromb Vasc Biol. 2000;20:1203–1208.[Abstract/Free Full Text]

12. Koller A, Sun D, Huang A, Kaley G. Corelease of nitric oxide and prostaglandins mediates flow-dependent dilation of rat gracilis muscle arterioles. Am J Physiol. 1994;267:H326–H332.[Abstract/Free Full Text]

13. Koller A, Kaley G. Endothelium regulates skeletal muscle microcirculation by a blood flow velocity-sensing mechanism. Am J Physiol. 1990;258:H916–H920.[Abstract/Free Full Text]

14. Durand P, Fortin LJ, Lussier-Cacan S, Davignon J, Blache D. Hyperhomocysteinemia induced by folic acid deficiency and methionine load—applications of a modified HPLC method. Clin Chim Acta. 1996;252:83–93.[Medline] [Order article via Infotrieve]

15. Matthias D, Becker CH, Riezler R, Kindling PH. Homocysteine induced arteriosclerosis-like alterations of the aorta in normotensive and hypertensive rats following application of high doses of methionine. Atherosclerosis. 1996;122:201–216.[Medline] [Order article via Infotrieve]

16. Huang A, Sun D, Kaley G, Koller A. Superoxide released to high intra-arteriolar pressure reduces nitric oxide-mediated shear stress- and agonist-induced dilations. Circ Res. 1998;83:960–965.[Abstract/Free Full Text]

17. Askari B, Bell-Quilley CP, Fulton D, Quilley J, McGiff JC. Analysis of eicosanoid mediation of the renal functional effects of hyperchloremia. J Pharmacol Exp Ther. 1997;282:101–107.[Abstract/Free Full Text]

18. Nygard O, Nordrehaug JE, Refsum H, Ueland PM, Farstad M, Vollset SE. Plasma homocysteine levels and mortality in patients with coronary artery disease. N Engl J Med. 1997;337:230–236.[Abstract/Free Full Text]

19. Kanani PM, Sinkey CA, Browning RL, Allaman M, Knapp HR, Haynes WG. Role of oxidant stress in endothelial dysfunction produced by experimental hyperhomocyst(e)inemia in humans. Circulation. 1999;100:1161–1168.[Abstract/Free Full Text]

20. Celermajer DS, Sorensen K, Ryalls M, Robinson J, Thomas O, Leonard JV, Deanfield JE. Impaired endothelial function occurs in the systemic arteries of children with homozygous homocystinuria but not in their heterozygous parents. J Am Coll Cardiol. 1993;22:854–858.[Abstract]

21. Tawakol A, Omland T, Gerhard M, Wu JT, Creager MA. Hyperhomocyst(e)inemia is associated with impaired endothelium-dependent vasodilation in humans. Circulation. 1997;95:1119–1121.[Abstract/Free Full Text]

22. Woo KS, Chook P, Lolin YI, Cheung AS, Chan LT, Sun YY, Sanderson JE, Metreweli C, Celermajer DS. Hyperhomocyst(e)inemia is a risk factor for arterial endothelial dysfunction in humans. Circulation. 1997;96:2542–2544.[Abstract/Free Full Text]

23. Chambers JC, McGregor A, Jean-Marie J, Obeid OA, Kooner JS. Demonstration of rapid onset vascular endothelial dysfunction after hyperhomocysteinemia: an effect reversible with vitamin C therapy. Circulation. 1999;99:1156–1160.[Abstract/Free Full Text]

24. Chambers JC, Obeid OA, Kooner JS. Physiological increments in plasma homocysteine induce vascular endothelial dysfunction in normal human subjects. Arterioscler Thromb Vasc Biol. 1999;19:2922–2927.[Abstract/Free Full Text]

25. Bellamy MF, McDowell IF, Ramsey MW, Brownlee M, Bones C, Newcombe RG, Lewis MJ. Hyperhomocysteinemia after an oral methionine load acutely impairs endothelial function in healthy adults. Circulation. 1998;98:1848–1852.[Abstract/Free Full Text]

26. Koller A, Huang A, Sun D, Kaley G. Exercise training augments flow-dependent dilation in rat skeletal muscle arterioles: role of endothelial nitric oxide and prostaglandins. Circ Res. 1995;76:544–550.[Abstract/Free Full Text]

27. Koller A, Huang A. Shear stress-induced dilation is attenuated in skeletal muscle arterioles of hypertensive rats. Hypertension. 1995;25:758–763.[Abstract/Free Full Text]

28. Durand P, Lussier-Cacan S, Blache D. Acute methionine load-induced hyperhomocysteinemia enhances platelet aggregation, thromboxane biosynthesis, and macrophage-derived tissue factor activity in rats. FASEB J. 1997;11:1157–1168.[Abstract]

29. Di Minno G, Davi G, Margaglione M, Cirillo F, Grandone E, Ciabattoni G, Catalano I, Strisciuglio P, Andria G, Patrono C, et al. Abnormally high thromboxane biosynthesis in homozygous homocystinuria: evidence for platelet involvement and probucol-sensitive mechanism. J Clin Invest. 1993;92:1400–1406.

30. Vesterqvist O, Green K. Urinary excretion of 2,3-dinor-thromboxane B₂ in man under normal conditions, following drugs and during some pathological conditions. Prostaglandins. 1984;27:627–644.[Medline] [Order article via Infotrieve]

31. Starkebaum G, Harlan JM. Endothelial cell injury due to copper-catalyzed hydrogen peroxide generation from homocysteine. J Clin Invest. 1986;77:1370–1376.

32. Upchurch GR Jr, Welch GN, Fabian AJ, Freedman JE, Johnson JL, Keaney JF Jr, Loscalzo J, Homocyst(e)ine decreases bioavailable nitric oxide by a mechanism involving glutathione peroxidase. J Biol Chem. 1997;272:17012–17017.[Abstract/Free Full Text]

33. Chen P, Poddar R, Tipa EV, Dibello PM, Moravec CD, Robinson K, Green R, Kruger WD, Garrow TA, Jacobsen DW. Homocysteine metabolism in cardiovascular cells and tissues: implications for hyperhomocysteinemia and cardiovascular disease. Adv Enzyme Regul. 1999;39:93–109.[Medline] [Order article via Infotrieve]

34. Outinen PA, Sood SK, Liaw PC, Sarge KD, Maeda N, Hirsh J, Ribau J, Podor TJ, Weitz JI, Austin RC. Characterization of the stress-inducing effects of homocysteine. Biochem J. 1998;332:213–221.

35. Jacobsen DW. Hyperhomocysteinemia and oxidative stress: time for a reality check? Arterioscler Thromb Vasc Biol. 2000;20:1182–1184.[Free Full Text]

36. Zou M, Jendral M, Ullrich V. Prostaglandin endoperoxide-dependent vasospasm in bovine coronary arteries after nitration of prostacyclin synthase. Br J Pharmacol. 1999;126:1283–1292.[Medline] [Order article via Infotrieve]

37. Huang A, Sun D, Koller A. Shear stress-induced release of prostaglandin H₂ in arterioles of hypertensive rats. Hypertension. 2000;35:925–930.[Abstract/Free Full Text]

38. Dai FX, Diederich A, Skopec J, Diederich D. Diabetes-induced endothelial dysfunction in streptozotocin-treated rats: role of prostaglandin endoperoxides and free radicals. J Am Soc Nephrol. 1993;4:1327–1336.[Abstract]

39. Lutz RJ, Cannon JN, Bischoff KB, Dedrick RL, Stiles RK, Fry DL. Wall shear stress distribution in a model canine artery during steady flow. Circ Res. 1977;41:391–399.[Abstract/Free Full Text]

40. Van den Berg M, Boers GH, Franken DG, Blom HJ, Van Kamp GJ, Jakobs C, Rauwerda JA, Kluft C, Stehouwert CD. Hyperhomocysteinaemia and endothelial dysfunction in young patients with peripheral arterial occlusive disease. Eur J Clin Invest. 1995;25:176–181.[Medline] [Order article via Infotrieve]

This article has been cited by other articles:

				E. Toth, A. Racz, J. Toth, P. M. Kaminski, M. S. Wolin, Z. Bagi, and A. Koller Contribution of polyol pathway to arteriolar dysfunction in hyperglycemia. Role of oxidative stress, reduced NO, and enhanced PGH2/TXA2 mediation Am J Physiol Heart Circ Physiol, November 1, 2007; 293(5): H3096 - H3104. [Abstract] [Full Text] [PDF]

				C. Cseko, Z. Bagi, and A. Koller Biphasic effect of hydrogen peroxide on skeletal muscle arteriolar tone via activation of endothelial and smooth muscle signaling pathways J Appl Physiol, September 1, 2004; 97(3): 1130 - 1137. [Abstract] [Full Text] [PDF]

				Z. Bagi, C. Cseko, E. Toth, and A. Koller Oxidative stress-induced dysregulation of arteriolar wall shear stress and blood pressure in hyperhomocysteinemia is prevented by chronic vitamin C treatment Am J Physiol Heart Circ Physiol, December 1, 2003; 285(6): H2277 - H2283. [Abstract] [Full Text] [PDF]

				N. Weiss, C. Keller, U. Hoffmann, and J. Loscalzo Endothelial dysfunction and atherothrombosis in mild hyperhomocysteinemia Vascular Medicine, August 1, 2002; 7(3): 227 - 239. [Abstract] [PDF]

				Z. Ungvari, A. Csiszar, Z. Bagi, and A. Koller Impaired Nitric Oxide-Mediated Flow-Induced Coronary Dilation in Hyperhomocysteinemia : Morphological and Functional Evidence for Increased Peroxynitrite Formation Am. J. Pathol., July 1, 2002; 161(1): 145 - 153. [Abstract] [Full Text] [PDF]

				A. Csiszar, Z. Ungvari, J. G. Edwards, P. Kaminski, M. S. Wolin, A. Koller, and G. Kaley Aging-Induced Phenotypic Changes and Oxidative Stress Impair Coronary Arteriolar Function Circ. Res., June 14, 2002; 90(11): 1159 - 1166. [Abstract] [Full Text] [PDF]

				Z. Bagi, Z. Ungvari, and A. Koller Xanthine Oxidase-Derived Reactive Oxygen Species Convert Flow-Induced Arteriolar Dilation to Constriction in Hyperhomocysteinemia: Possible Role of Peroxynitrite Arterioscler. Thromb. Vasc. Biol., January 1, 2002; 22(1): 28 - 33. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Bagi, Z. Articles by Koller, A. Search for Related Content PubMed PubMed Citation Articles by Bagi, Z. Articles by Koller, A. Related Collections Animal models of human disease Pathophysiology Other arteriosclerosis Peripheral vascular disease Endothelium/vascular type/nitric oxide