Abstract 386: Circulating Endothelial Microparticles, Elevated Blood Pressure and Endothelin-1 Mediated Vasoconstrictor Tone
Clinical interest in circulating microparticles originating from both endothelial cells and platelets has increased due to their putative role in inflammation, endovascular function, angiogenesis and thrombosis. Elevated blood pressure is associated with profound endothelial dysfunction, particularly enhanced endothelin (ET)-1-mediated vasoconstrictor tone. There is some evidence to suggest that circulating microparticles are influenced by blood pressure and may contribute to associated vascular abnormalities. As part of an ongoing study, we are determining: 1) whether circulating endothelial (EMP) and platelet (PMP) microparticles are higher in adults with elevated blood pressure (SBP >130 mmHg) and if so; 2) if these microparticles are associated with ET-1 mediated vasoconstriction. To date, 22 sedentary, non-obese middle-aged adults have been studied: 11 normotensive (age: 55+2 yr; 7 M/4 F; BP: 118/74+3/2 mm Hg) and 11 prehypertensive/hypertensive (age: 55+2 yr; 7 M/4 F; BP: 140/85+2/3 mm Hg). All subjects were free of overt cardiometabolic disease. EMPs and PMPs were measured in platelet-poor plasma by flow cytometry. EMPs were defined as CD31+/CD42b- events and PMPs were defined as CD31+/CD42+ events. Forearm blood flow (FBF: plethysmography) responses to intra-arterial infusion of BQ-123 (100 nmol/min; for 60 min), a selective ETA receptor antagonist. EMPs were ~70% higher (p<0.01) in the prehypertensive/hypertensive (39072+3951 MP/μL) compared with normotensive (22726+2552 MP/μL). There was no difference in EMPs with the elevated blood pressure group between the prehypertensive (n=5) and hypertensive (n=6) adults. PMPs were not significantly different between the groups (503+132 vs 431+80 MP/μL). Resting FBF increased ~40% (p<0.01) in response to BQ-123 in the prehypertensive/hypertensive group only. EMPs were significantly correlated with systolic blood pressure (r=0.68) and peak FBF response to ETA receptor blockade (r=0.61). These initial results indicate that circulating EMPs, but not PMPs, are elevated in prehypertensive/hypertensive adults. Moreover, circulating EMPs are associated with systolic blood pressure and enhanced ET-1 mediated vasoconstrictor tone.
Author Disclosures: C.A. Beckstrom: None. T.D. Bammer: None. C. Dow: None. G. Lincenberg: None. K.J. Diehl: None. J.J. Greiner: None. B.L. Stauffer: None. C.A. DeSouza: None.
- © 2014 by American Heart Association, Inc.