Ethnic differences in beta-1-adrenoceptor sensitivity.

In the light of reports that beta-adrenoceptor-blocking drugs seem to be ineffective in Black hypertensives, the effects of penbutolol on exercise-induced tachycardia were assessed in 6 Black and 6 White healthy volunteers. After a standardized breakfast at 08h00 the subjects received either intravenous penbutolol or placebo at 08h45, on a randomized double-blind basis. At each test session subjects were exercised for 5 minutes on a bicycle ergometer, the load predetermined to increase their heart rates to +/- 130/min. Recordings, spaced at 30-minute intervals, commenced 45 minutes after the injection. The results indicate that Black volunteers require a higher dose of penbutolol than Whites to achieve a similar degree of beta 1-adrenoceptor blockade. It also appears that the maximal response is lower in Blacks.

RCT Entities:   Population Interventions Outcomes