Negative inotropic activity of antilaminin IgG: participation of cholinergic mechanisms

1. Antilaminin IgG decreased the dF/dt of mouse isolated atria and inhibited the mechanical effect of acetylcholine in a non-competitive fashion. 2. Inhibitors of nicotinic and muscarinic cholinoceptors impaired the negative inotropic action of antilaminin IgG in mouse isolated atria. Hemicholinium and tetrodotoxin also reduced the response while the antihistamine, pyrilamine was without effect. 3. These results suggest that antilaminin IgG modulates cholinergic function in mouse isolated atria. Possible mechanisms are discussed.