Racial differences in renal vascular response to angiotensin blockade with captopril or candesartan

OBJECTIVE: We compared the renal vascular response to captopril and candesartan among nondiabetic, normotensive black and white participants to explore angiotensin-converting enzyme-independent generation of angiotensin II. METHODS: Thirteen black individuals and 10 white individuals in low-salt balance were given captopril and candesartan on sequential study days, and the renal plasma flow responses to these agents were measured. RESULTS: Consistent with our prior observations, white individuals demonstrated a strong, significant correlation between responses to these drugs (r = 0.78, P = 0.008) and a significantly greater increase in the renal plasma flow in response to candesartan compared with captopril (104.2 +/- 26.8 versus 52.4 +/- 24.3 ml/min per 1.73 m; P = 0.03). In black participants, however, no correlation between responses to captopril and to candesartan was observed (r = 0.22, P = 0.47) and there was no difference in the renal plasma flow response between the two drugs (90.4 +/- 13.0 versus 80.4 +/- 15.3 ml/min per 1.73 m; P = 0.59). The difference in the response to the two drugs was significantly higher among white participants compared with black participants (P = 0.03). CONCLUSION: We confirmed the contribution of an angiotensin-converting enzyme-independent pathway for angiotensin II generation in the kidneys of nondiabetic, normotensive white, but not black, individuals.