Abnormal cardiopulmonary baroreflexes in normotensive young subjects with a family history of essential hypertension.

Cardiopulmonary baroreflex control of forearm vascular resistance (FVR) and arterial baroreflex control of heart rate were compared between 12 normotensive subjects with hypertensive relatives (group A, 19.4 +/- 0.2 years) and 12 normotensive subjects with no family history of hypertension (group B, 19.5 +/- 0.3 years). Cardiopulmonary baroreflexes were evaluated using lower body negative pressure (LBNP) at -20 mmHg, and arterial baroreflexes were measured by Oxford phenylephrine method. Resting arterial pressure, central venous pressure, heart rate, cardiac index, total peripheral resistance, and FVR were not different between the two groups. Arterial baroreflex slope (BS) and reflex increases in FVR during LBNP were significantly lower in group A than in group B (11.4 +/- 0.9 vs. 17.1 +/- 1.1 ms/mmHg, 37.7 +/- 8.1% vs. 86.5 +/- 18.7%, respectively). There was significant correlation between %FVR and BS (r = 0.59; p less than 0.01). These results suggest that both cardiopulmonary and arterial baroreflexes are impaired in normotensive young subjects with a family history of hypertension.