Apparent racial difference in response to angiotensin I infusion.

Angiotensin I was infused into 16 healthy volunteers, 8 blacks and 8 whites with diastolic blood pressures below 75 mm Hg and the infusion rate increased at 3 min intervals until a diastolic blood pressure of equal to or greater than 95 mm Hg was achieved. Blacks exhibited a significantly greater angiotensin I sensitivity needing 1.8 micrograms/min as opposed to 3.9 micrograms/min in whites to achieve the target blood pressure. Plasma renin activities were similar in the two groups, but blacks had significantly higher urinary sodium values than whites, 223 mmol per 24 h as compared to 121 mmol per 24 h. It is concluded that the differences in response could be largely due to differences in dietary sodium intake. These factors need to be carefully considered when using angiotensin I infusion as a pharmacodynamic model for studying the effects of ACE inhibitors.