PARTICIPATION OF CYTOSKELETON IN THE EFFECT OF ANTILAMININ IGG ON CARDIAC CHOLINOCEPTORS

1 We have previously demonstrated a molecular relationship between laminin and cardiac cholinoceptors. 2 We have now explored the participation of cytoskeletal proteins in the interaction between an antilaminin IgG with cardiac cholinoceptors. 3 Antilaminin IgG, whilst it specifically reacts with laminin molecules was able to induce cardiac cholinoceptor activation; acting like an agonist, decreasing cyclic AMP concentrations, reducing heart contractility and increasing phosphoinositide turnover. 4 Antilaminin IgG also interfered with the binding of a radiolabelled muscarinic antagonist, [SH]quinuclidinyl benzilate. Colchicine and cytochalasin B, drugs that are able to prevent microfilament and microtubule polimerization, impaired the binding of antilaminin IgG to muscarinic cholinoceptors. 5 Cytochalasin B but not colchicine modified the muscarinic cholinoceptor effects mediated by regulatory G proteins (cyclic AMP and contractility) induced by antilaminin IgG. 6 It was demonstrated, by immunofluorescence, that none of these disrupting drugs altered the specific recognition of the antibody by its antigen. 7 These data indirectly suggest the participation of the cytoskeleton in the laminin and cholinergic receptor association.