P3.18 ENDOTHELIAL FUNCTION BUT NOT IN INTIMA-MEDIA THICKNESS RELATES TO RENIN STATUS IN A MULTI-ETHNIC GROUP OF YOUNG HEALTHY ADULTS

Abstract

Subjects of African and African-Caribbean ethnicity have been reported to have lower plasma renin activity (PRA), decreased endothelium-dependent vasomotor function and increased intima-media thickening relative to white European subjects. We explored whether vascular structure and function might be associated with renin status, since both may be influenced by endothelium-derived nitric oxide (NO). Flow mediated dilation (FMD, a measure of endothelium-derived NO) of the brachial artery and common carotid intima-media thickness (CIMT) were measured using high resolution ultrasound in a multi-ethnic group of 143 subjects (mean ± SD 30±10 years) including 84 black subjects of African or African-Caribbean self defined ethnicity; the remainder were of white European ethnicity. Subjects were additionally characterized by anthropometric and biochemical measurements including plasma renin activity (PRA) and underwent ambulatory blood pressure monitoring. PRA was lower (0.6 ± 0.67 vs. 0.9 ± 0.6 ng ml−1 hr−1, medians ± IQR, P< 0.092) and IMT greater (0.47± 0.09 vs. 0.43 ± 0.08 mm) in black compared to white subjects. FMD tended to be lower in black compared to white subjects but the difference was not significant. FMD was independently correlated with PRA after adjustment for age, ethnicity, sex and blood pressure (standardized regression coefficient 0.31, P<0.005). However, IMT was not significantly correlated with FMD nor with PRA. These results suggest that availability of endothelium-derived NO is closely associated with PRA but does not explain ethnic differences in CIMT.