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

Although a slightly elevated office blood pressure (BP) has been reported i n several studies, little is known about the prolonged resting blood pressu re, heart rate (HR) and baroreflex sensitivity (BRS) of prehypertensive sub jects with a family history of hypertension. Office blood pressure, prolong ed resting (1 h) BP and HR were measured in 25 young normotensives with a p ositive family history of hypertension (FH+) and 25 young normotensives wit h a negative family history of hypertension (FH-), matched for age, sex, an d body mass index. After BP and HR measurements, blood samples were collect ed for the determination of norepinephrine, plasma renin activity and aldos terone levels, and baroreflex sensitivity was then tested. Casual BP, prolo nged 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 lev el was significantly higher in the FH+ group (220.1 +/- 104.5 pg/ml) than i n the FH- group (169.1 +/- 63.3 pg/ml). Baroreflex sensitivity to tachycard ia (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 rest ing blood pressure, heart rate and plasma norepinephrine levels than the FH - group (P<0.05), suggesting an increased sympathetic tone in these subject s. The reflex tachycardia was depressed in the FH+ group.