Biobehavioral Mechanisms of Blood Pressure Regulation

BACKGROUND:

Hypertension is more prevalent in Black than white men, and is more prevalent in men than women. Furthermore, even controlling for blood pressure, concentric left ventricular hypertrophy, an early structural adaptation of hypertension, is more prevalent in Black than white men, and more prevalent in men than women. Concentric left ventricular hypertrophy is the strongest predictor, other than age, of the cardiovascular morbidity associated with high blood pressure.

DESIGN NARRATIVE:

In a biracial sample, concentric left ventricular hypertrophy and concentric remodelling were assessed by echocardiographic measures of left ventricular mass and relative wall thickness. Laboratory procedures were used to: (i) assess hemodynamic and neurohumoral responses during exposure to a diverse battery of physical and psychological stressors, and; (ii) evaluate alpha and beta adrenergic receptor responsiveness, baroreceptor reflex gain and minimal forearm vascular resistance. Since blood pressure during a typical workday was an established predictor of left ventricular hypertrophy, it was also assessed. A new biobehavioral model was tested that implicated the hemodynamic pattern of behaviorally-evoked pressor responses in the pathogenesis of concentric left ventricular hypertrophy. One prediction of this model was that a predisposition to exhibit increased vascular resistance during stress (characteristic of black men) would favor the development of concentric hypertrophy. Thus, systemic vascular resistance responses, evaluated in the laboratory, were hypothesized to independently predict left ventricular mass and relative wall thickness, even after controlling for established risk factors, including workday blood pressure. Sympathetic nervous system function was examined to test hypothesized mechanisms responsible for race and gender differences in the hemodynamic patterns of blood pressure regulation. The results of these studies emphasized the importance of race and gender in prescribing pharmacological and/or behavioral treatment for hypertensive heart disease.