Antilaminin IgG binds and interacts with cardiac cholinergic receptors.

Antilaminin IgG bound to cholinergic muscarinic receptors of normal mice heart and simulated the biological effect of a cholinergic agonist. Antilaminin IgG interfered with the binding of the radiolabelled muscarinic antagonist, (-)-[3H]quinuclidinyl benzilate, in a noncompetitive fashion. The interaction of antilaminin IgG with the muscarinic cholinergic receptor increased production of cGMP and decreased production of cAMP. Antilaminin IgG also decreased the contractile tension of mouse atria. Both the mechanical and enzymatic effect of antilaminin IgG required the activation of the muscarinic cholinergic system because they were blunted by atropine and mimicked by acetylcholine.