Limb Vascular Responsiveness to 3-Adrenergic Receptor Stimulation in Patients With Congestive Heart Failure

Background. In patients with congestive heart failure, the chronotropic and inotropic responses to f3-adrenergic agonists are reduced. It is not known whether desensitization of peripheral ,B-adrenoceptors accounts for impaired limb vasodilation in these patients. Accordingly, we studied 14 normal subjects and 13 age-matched patients with congestive heart failure. Methods and Results. To distinguish vasodilation mediated by 3-adrenoceptors and adenylate cyclase from that mediated by stimulation of guanylate cyclase, each subject received intrabrachial artery infusions of isoproterenol (1-100 ng/min) and sodium nitroprusside (0.3-10 ,ug/min), respectively. Forearm blood flow was determined by venous occlusion plethysmography. Maximal vasodilative potential, determined during reactive hyperemia, was reduced in the patients with congestive heart failure. The maximal forearm blood flow response to isoproterenol