Forearm vascular responsiveness to α1- and α2-adrenoceptor stimulation in patients with congestive heart failure

Abstract

Background: The α-adrenergic component of the sympathetic nervous system plays a major role in the pathophysiology, clinical manifestations, and natural history of human congestive heart failure (CHF). However, the functional integrity of vascular α1- and α2-adrenoceptors in CHF remains to be elucidated. The present study was designed to assess the vascular responsiveness of α1- and α2-adrenoceptors in patients with CHF. Methods and Results: To evaluate α1- and α2-adrenoceptor responsiveness, we studied the effects of the regional infusion into the brachial artery of increasing doses of phenylephrine (a selective α1-adrenoceptor agonist) and BHT 933 (a selective α2-adrenoceptor agonist) on vascular responses in 12 healthy subjects and in 24 patients with CHF secondary to primary dilated cardiomyopathy or ischemic heart disease. Left ventricular ejection fraction was measured by radionuclide angiography, and forearm blood flow was determined by venous occlusion plethysmography. Phenylephrine reduced forearm blood flow in normal subjects from 5.2±0.9 to 2.5±0.6 mL per 100 mL of tissue/min (P