Abnormal baroreflex control of heart rate in normotensive young subjects with a family history of essential hypertension.

This study was performed to determine whether baroreflex control of heart rate is impaired in young normotensive subjects with hypertensive relatives. Blood pressure, baroreflex function, pressor response to phenylephrine, aortic distensibility (pulse pressure/stroke volume) and minimal forearm vascular resistance (minFVR) were assessed in 13 normotensive subjects with hypertensive relatives (group A) and 11 normotensive subjects with no family history of hypertension (group B). Baroreflex sensitivity was significantly lower in group A than in group B (9.4 +/- 1.7 versus 17.5 +/- 1.7 ms/mmHg, P less than 0.01), although blood pressure, aortic distensibility and minFVR were not different between two groups. Pressor response to phenylephrine was identical for both groups. These results suggest that baroreflex control of heart rate is impaired in normotensive young subjects with hypertensive relatives and this defect may be inherited rather than the result of elevated blood pressure and decrease aortic distensibility.