Modification of G regulatory protein mediated actions by the interaction of histocompatibility antigens with cardiac muscarinic cholinergic receptors.
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.
Cremaschi
G
G
Centro de Estudios Farmacológicos Botánicos (CEFYBO), Consejo Nacional de Investigaciones (CONICET), Buenos Aires.
Gorelik
G
G
Genaro
A
A
Borda
E
E
Sterin-Borda
L
L
D000818:Animals; D001667:Binding, Competitive; D000242:Cyclic AMP / Q000032:analysis; D006152:Cyclic GMP / Q000032:analysis; D019204:GTP-Binding Proteins / Q000378:metabolism*; D015395:Histocompatibility Antigens Class I / Q000378:metabolism*; D007074:Immunoglobulin G / Q000378:metabolism; D066298:In Vitro Techniques; D007295:Inositol Phosphates / Q000032:analysis; D007518:Isoantibodies / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism*; D011813:Quinuclidinyl Benzilate / Q000494:pharmacology; D011869:Radioligand Assay; D011976:Receptors, Muscarinic / Q000378:metabolism*; D015290:Second Messenger Systems; D010738:Type C Phospholipases / Q000378:metabolism
D015395:Histocompatibility Antigens Class I; D007074:Immunoglobulin G; D007295:Inositol Phosphates; D007518:Isoantibodies; D011976:Receptors, Muscarinic; D011813:Quinuclidinyl Benzilate; D000242:Cyclic AMP; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; D006152:Cyclic GMP