Identification of α1 -Adrenergic Receptors on Sarcolemma From Normal Subjects and Patients With Idiopathic Dilated Cardiomyopathy: Characteristics and Linkage to GTP-Binding Protein

Discontinuous density sucrose gradient centrifugation was used to isolate membrane vesicles from the left ventricle of three normal subjects (one prospective organ donor and two traffic victims whose hearts were obtained 1 hour after death) and nine patients undergoing cardiac transplantation as a consequence of idiopathic dilated cardiomyopathy. Sarcolemma-enriched subcellular fractions, detected in the interface between 8.55percent; and 25percent; sucrose, were identified by the increased activity of Na, K-ATPase and by enrichment in β-adrenergic receptor density. The density of β-adrenergic receptors was lower in vesicles from diseased hearts (610±71 fmol/mg protein) than in vesicles from normal hearts (1,410±226 fmol/mg protein; p