Modification of G regulatory protein mediated-action by HC antigens. Interactions with cardiac muscarinic cholinergic receptors.

CREMASCHI GA ; GORELIK G; GENARO AM; BORDA E; STERIN-BORDA L

BIOCHEMICAL PHARMACOLOGY

PERGAMON-ELSEVIER SCIENCE LTD

Año: 1992 vol. 43 p. 2493 - 2501

0006-2952

In this work we characterized the interaction of class I histocompatibility (HC) antigens (Ag) with cardiac cholinergic receptors by means of specific radioligand binding and by production of cholinergic-mediated cellular transmembrane signals. Alloimmune as well as anti-class I but not anti-class II antibodies were able to inhibit in an allosteric manner the binding of [3H]quinuclidinyl benzilate to cardiac membrane. Moreover, alloantibody could modify all of the muscarinic cholinergic effects mediated by a G regulatory protein, i.e. decrement of atria contractility, inhibition of cAMP stimulation, and activation of the turnover of phosphoinositides via phospholipase C. The cGMP production was not altered by the alloantibody. The data indirectly indicated that HC-Ag-muscarinic cholinergic interactions trigger all the cholinergic functions related to G proteins. The induction of intracellular second messengers by class I antigens and hormone-receptor interactions is discussed.