Blunted cardiovagal arterial baroreflex gain to acute hypertension in young black men

Abstract

Blacks are at an elevated risk for developing hypertension. Although carotid baroreflex control of heart rate in blacks has been investigated, little is known regarding integrated arterial baroreflex (ABR) control of the heart in blacks. Thus, we tested the hypothesis that cardiovagal ABR is reduced in blacks compared to whites. The slope of the relationship (i.e., gain) between changes in systolic blood pressure and r‐r interval were determined in 16 non‐hypertensive men (7 black and 9 white, age 18–27 yr) using 100μg iv bolus of sodium nitroprusside (NTP) followed 1 min later by 150μg bolus of phenylephrine (PE) during rest (3 trials). In addition to analysis of the complete mod‐Ox trials (overall ABR gain), separate linear analyses of the NTP (hypotenion) and the PE (hypertension) phases were also performed. Overall ABR gain was not different between racial groups (black: 14±4 vs white: 13±4 ms/mm Hg, p=0.64). Although the gain for the NTP phase was also not different between groups (p=0.17), the gains for the PE phase were significantly reduced in blacks (10±4) compared to whites (18±10 ms/mm Hg; p=0.04). These findings indicate that blacks have diminished ABR responses to acute hypertensive stimuli and support racial differences in cardiovagal ABR function between black and white men.Supported by NIH R15HL096103 (DMK) and RO1 HL093167 (PJF)