Autonomic abnormalities demonstrable in young normotensive subjects who are children of hypertensive parents.

Although a slightly elevated office blood pressure (BP) has been reported in several studies, little is known about the prolonged resting blood pressure, heart rate (HR) and baroreflex sensitivity (BRS) of prehypertensive subjects with a family history of hypertension. Office blood pressure, prolonged resting (1 h) BP and HR were measured in 25 young normotensives with a positive family history of hypertension (FH+) and 25 young normotensives with a negative family history of hypertension (FH-), matched for age, sex, and body mass index. After BP and HR measurements, blood samples were collected for the determination of norepinephrine, plasma renin activity and aldosterone levels, and baroreflex sensitivity was then tested. Casual BP, prolonged resting BP and heart rate were significantly higher in the FH+ group (119.9 +/- 11.7/78.5 +/- 8.6 mmHg, 137.3 +/- 12.3/74.4 +/- 7.9 mmHg, 68.5 +/- 8.4 bpm) compared to the FH- group (112.9 +/- 11.4/71.2 +/- 8.3 mmHg, 128.0 +/- 11. 8/66.5 +/- 7.4 mmHg, 62.1 +/- 6.0 bpm). Plasma norepinephrine level was significantly higher in the FH+ group (220.1 +/- 104.5 pg/ml) than in the FH- group (169.1 +/- 63.3 pg/ml). Baroreflex sensitivity to tachycardia (0.7 +/- 0.3 vs 1.0 +/- 0.5 bpm/mmHg) was depressed in the FH+ group (P<0.05). The FH+ group exhibited higher casual blood pressure, prolonged resting blood pressure, heart rate and plasma norepinephrine levels than the FH- group (P<0.05), suggesting an increased sympathetic tone in these subjects. The reflex tachycardia was depressed in the FH+ group.