EFFECTS OF ALPHA(1)-BLOCKADE ON MAXIMAL VASCULAR CONDUCTANCE IN YOUNGBORDERLINE HYPERTENSIVES

This study was conducted to determine if reducing sympathetic tone wit h alpha(1)-adrenergic receptor blockade affected the maximal forearm v ascular conductance (FVCmax; reactive hyperemia) responses in young bo rderline hypertensives and normotensive controls. The FVC response fol lowing ischemia (14 min arterial occlusion with 3 min of hand exercise ) was determined after systemic alpha(1)-blockade (5 mg prazosin in pr eceding 24 h) in hypertensives (n=11, MAP=110+/-1, age=24.5+/-1.1, (x) over bar+/-SEM) and normotensives (n=13, MAP=82+/-1, age=22.5+/-0.3). During the placebo trial, resting FVC was lower in the hypertensives than the normotensives (.0472+/-.0073 vs. 0755+/-.0095 units; P<.05). During alpha(1)-blockade, FVC did not differ between the groups. Withi n each group, FVCmax did not differ significantly between either trial . During placebo, FVCmax was lower (P<.05) in the hypertensives (.3485 +/-.0335 vs. 5641+/-.0503 units) and remained so during alpha(1)-block ade (.4048+/-.0520 vs .5286+/-.0275 units; P<.05). These data suggest that alpha(1)-blockade does not increase FVCmax in borderline hyperten sives and that both functional and structural changes in the periphera l vasculature are involved in the blood pressure elevations seen in th is group.