Effects of alpha 1-blockade on maximal vascular conductance in young borderline hypertensives.
This study was conducted to determine if reducing sympathetic tone with alpha 1-adrenergic receptor blockade affected the maximal forearm vascular conductance (FVCmax, reactive hyperemia) responses in young borderline hypertensives and normotensive controls. The FVC response following ischemia (14 min arterial occlusion with 3 min of hand exercise) was determined after systemic alpha 1-blockade (5 mg prazosin in preceding 24 h) in hypertensives (n = 11, MAP = 110 +/- 1, age = 24.5 +/- 1.1, mean +/- 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. Within 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-blockade (.4048 +/- .0520 vs .5286 +/- .0275 units; P < .05). These data suggest that alpha 1-blockade does not increase FVCmax in borderline hypertensives and that both functional and structural changes in the peripheral vasculature are involved in the blood pressure elevations seen in this group.
Franke
W D
WD
Department of Health and Human Performance, Iowa State University, Ames 50011, USA.
Tegeler
N B
NB
D058668:Adrenergic alpha-1 Receptor Antagonists; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D016022:Case-Control Studies; D004311:Double-Blind Method; D005542:Forearm; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006940:Hyperemia / Q000150:complications / Q000188:drug therapy*; D006973:Hypertension / Q000150:complications / Q000188:drug therapy*; D007511:Ischemia / Q000188:drug therapy; D011224:Prazosin / Q000494:pharmacology*; D014664:Vasodilation / Q000187:drug effects*
D058668:Adrenergic alpha-1 Receptor Antagonists; D000317:Adrenergic alpha-Antagonists; D011224:Prazosin