THE BETA(1)-ADRENOCEPTOR AS ANTIGEN FUNCTIONAL-ASPECTS

The sera of patients with myocarditis and idiopathic dilated cardiomyo pathy contain agonistic autoantibodies that bind to the beta(1)-adreno ceptor. These antibodies recognize epitopes on either the first or sec ond extracellular loop of this receptor and exert in cultured neonatal rat heart myocytes a positive chronotropic effect. This effect is eli minated by beta(1)-adrenoceptor blockade as well as by peptides corres ponding to the first or second extracellular loop of the human beta(1) -adrenoceptor The antibodies realize their effects mainly via the beta -adrenoceptor-adenylate cyclase-protein kinase A cascade.