Effects of metoprolol on myocardial β-adrenoceptors and Giα-proteins in patients with congestive heart failure

Objective: In human heart failure downregulation of β-adrenoceptors and upregulation of Gi-protein α-subunits (Giα) results desensitization of the myocardial β-adrenergic signal transduction pathway and reduced positive inotropic effects of catecholamines. Metoprolol treatment has been shown to restore the reduced β-adrenoceptor density in dilated cardiomyopathy. The main objective of the present study was to investigate whether metoprolol also decreases the elevated inhibitory Giα levels in patients suffering from congestive heart failure.