Spontaneous Baroreflex Sensitivity in Normotensive African-American Men

Abstract

Purpose: African-American men (AAM) have a greater risk of hypertension (HTN) than Caucasian men (CM). To reduce this risk, determining the differences in mechanisms involved in HTN and understanding the relationship between these mechanisms and factors affecting blood pressure (BP) in AAM and CM is necessary. One such mechanism is spontaneous baroreflex sensitivity (sBRS) and two factors are cardiorespiratory fitness (CRF) and arterial stiffness (AS). The aims of this study were to determine, firstly, whether there are differences in sBRS between young, normotensive AAM and CM, and secondly, to determine if CRF and AS are significant predictors of sBRS in young, normotensive AAM and CM. Methods: Twenty-three normotensive AAM and 36 CM were recruited from Southern Connecticut State University. Measures included anthropometric, sBRS (alpha-index), and CRF (maximal oxygen consumption [VO 2max ]), as well as AS (carotid-femoral pulse wave velocity [Cf-PWV]). Independent t-tests were used to determine differences between groups and multiple regression analysis was used to determine how much of the variation in sBRS was explained by CRF and AS. Results: The sBRS was significantly lower in AAM (10.3 ± 3.8 ms/mmHg) vs. CM (13.3 ± 5.7 ms/ mmHg), P = 0.03. CRF and AS were not significant predictors of sBRS in AAM (P = 0.25) and CM (P = 0.30). There was no relationship between, sBRS, CRF and AS; CRF was significantly reduced in AAM vs. CM (45.1 ± 6.3 vs. 52.1 ± 7.5 mL•kg −1 •min −1 , P ≤ 0.001). Conclusions: Young normotensive AAM demonstrated significantly lower sBRS vs. CM, irrespective of having fair CRF and normal BP.