Effects of prazosin on forearm resistance and capacitance vessels

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Abstract
The effects of oral prazosin on the peripheral circulation were evaluated in 10 subjects, including 7 patients with chronic congestive failure due to coronary heart disease. To achieve this purpose the actions of 30 to 50 µg/kg body weight prazosin were assessed on both the forearm arteriolar and venous beds simultaneously with the use of the limb plethysmographic technique. Prazosin produced marked decline of forearm venous tone (FVT) from 44.5 ± 12.3 to 14.3 ± 3.1 mm Hg/ml (p < 0.01) concomitant with marked decrease in forearm vascular resistance (FVR) from 70.2 ± 11.4 to 48.4 ± 4.9 mm Hg/ml/100 gm/min (p < 0.05) which persisted for at least 60 mins without change in heart rate. These findings, demonstrating that prazosin induces systemic venodilation and peripheral arteriolodilation, indicate potential benefits of the oral drug for relief of pulmonary congestion and elevations of cardiac output in patients with chronic congestive heart failure.