Baroreflex sensitivity and heredity in essential hypertension

Background. Abnormalities in baroreflex control of heart rate may be important in the pathogenesis of essential hypertension. Methods and Results. To investigate the influence of heredity on baroreflex function, we measured baroreflex sensitivity in 40 untreated patients with essential hypertension grouped by the presence (FH+) or absence (FH-) of a family history of hypertension and in 24 normotensive counterparts. Baroreflex sensitivity was assessed by both high-pressure (phen-ylephrine bolus) and low-pressure (amyl nitrite inhalation) stimuli. Subject groups were matched for age, blood pressure, body weight, and race. Baroreflex sensitivity (in milliseconds per millimeter of mercury) assessed by amyl nitrite inhalation was 24.3 2.8 in FH-normotensives, 12.3±1.7 in FH+ normotensives, 15.4±3.3 in FH- hypertensives, and 8.1±+1.2 in FH+ hypertensives. Baroreflex sensitivity assessed by phenylephrine bolus was 28.8±+5.6 in FH- normotensives, 19.3±2.8 in FH+ normotensives, 19.1±2.0 in Fl- hypertensives, and 13.6±1.3 in FH+ hypertensives. Two-factor analysis of variance showed significant effects on baroreflex sensitivity for blood pressure status (normotensive versus hypertensive) and for family history of hypertension. After control line (controlling) for the effects of severa