Blacks Have a Greater Sensitivity to alpha(1)-Adrenoceptor-Mediated Venoconstriction Compared With Whites

作者：Adefurin Abiodun; Ghimire Laxmi V; Kohli Utkarsh; Muszkat Mordechai; Sofowora Gbenga G; Paranjape Sachin Y; Stein C Michael; Kurnik Daniel^*

来源：Hypertension, 2013, 61(4): 915-920.

DOI：10.1161/HYPERTENSIONAHA.111.00854

• alpha-1 adrenergic receptor
• ethnicity
• hypertension
• phenylephrine
• vasoconstriction

Blacks have increased hemodynamic responses to both physiological and pharmacological adrenergic stimulation compared with whites, and this may contribute to the greater prevalence of hypertension in this ethnic group. A small study suggested enhanced alpha(1)-adrenoreceptor-mediated arterial vasoconstriction in the forearm vasculature of blacks compared with whites, but it is unknown whether this reflects a generalized vascular phenomenon. The objective of this study was to examine the hypothesis that there are ethnic differences in venous alpha(1)-adrenoreceptor responsiveness. Using a linear variable differential transformer, we measured local dorsal hand vein responses to increasing doses of the selective alpha(1)-adrenoreceptor agonist, phenylephrine, in 106 subjects (64 whites and 42 blacks). There was wide interindividual variability in responses to phenylephrine. The dose that produced 50% of maximal constriction (ED50) ranged from 11 to 5442 ng/min, and maximal venoconstriction (E-max) ranged from 13.5% to 100%. Blacks (geometric mean ED50 =172 ng/min; 95% confidence interval, 115-256 ng/min) were more sensitive to phenylephrine than whites (310 ng/min; 95% confidence interval, 222-434 ng/min; unadjusted P=0.026; adjusted P=0.003). Median E-max was slightly higher in blacks (89%; interquartile range, 82% to 98%) compared with whites (85%; interquartile range, 75% to 95%; P=0.07). Taken together with previous findings in arterial vessels, our results suggest a generalized increased sensitivity to alpha(1)-adrenoreceptor-mediated vasoconstriction in blacks. Increased vascular alpha-adrenoreceptor sensitivity could predispose to hypertension, and future studies addressing the contribution of this mechanism to ethnic differences in the prevalence of hypertension will be of interest. (Hypertension. 2013;61:915-920.)

• 出版日期2013-4