Negative inotropic activity of antilaminin IgG: participation of cholinergic mechanisms

Participation of cytoskeleton in the effect of antilaminin IgG on cardiac cholinoceptors

“…We have previously shown that antilaminin IgG binding to laminin in heart tissue, may interfere with cholinoceptors and may activate a transduction system common to the one linked to the muscarinic cholinoceptor and thus, may induce a cholinoceptor biological response (Bacman et al, 1989;. The cholinoceptor effects of antilaminin IgG were prevented by preincubating the antibody with the specific antigen laminin.…”

“…Male rabbits of approximately 2.5 kg, were injected intra-dermally with an emulsion prepared of equal parts of laminin (1 mg ml') and complete Freund's adjuvant as previously described (Bacman et al, 1989;. Injections were repeated three times with 0.5 mg at intervals of 15 days.…”

“…The atria were separated from the ventricles, attached to a glass holder, and immersed in a tissue chamber containing KRB solution gassed with 5% CO2 in 02 and maintained at pH 7.4 and 30± 0.3°C. The contractile activity of paced atria in terms of dF/dt was recorded and assessed as previously reported (Borda et al, 1984;Bacman et al, 1989;. Control values (= 100%) refer to dF/dt before the addition of drugs or normal or antilaminin IgG.…”

“…We recently demonstrated an interaction between an antilaminin IgG with cardiac cholinoceptors (Bacman et al, 1989;. Concerning cardiac muscarinic cholinoceptors and laminin interactions, we have found that antilaminin IgG, whilst specifically recognizing laminin molecules, was able to induce cardiac cholinoceptor activation leading to a change in contractile parameters and other intracellualr events mediated by regulatory GTP-binding (G) proteins (Bacman et al, 1990).…”