title: Modification of sarcolemmal enzymes by chagasic IgG and its effect on cardiac contractility.
abstract: It has been shown that sera from chagasic patients contain an antibody which binds to beta-adrenoceptors of myocardium and modulates their activity. Chagasic IgG triggered a marked stimulation of myocardial contractility with an increase in intramyocardial cyclic AMP and inhibition of (Na+ + K+)-ATPase activity. Both the mechanical and enzymatic effects of the IgG could be prevented by beta-adrenoceptor blockade or after the absorption of chagasic IgG with turkey red blood cells. In contrast, guinea pig red blood cells were unable to remove the beta-reactivity of chagasic IgG. These findings suggest that the IgG from chagasic patients increases myocardial contractility by behaving as a beta-agonist. This effect is likely related to stimulation of the adenylate cyclase coupled to the cardiac beta-adrenoceptor.
mesh_terms: D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D002598:Chagas Cardiomyopathy / Q000097:blood / Q000276:immunology*; D014355:Chagas Disease / Q000276:immunology* / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D006168:Guinea Pigs; D006801:Humans; D007074:Immunoglobulin G / Q000494:pharmacology*; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000276:immunology / Q000378:metabolism*; D051381:Rats; D012508:Sarcolemma / Q000201:enzymology; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism; D014422:Turkeys
chemical_list: D000067956:Adenylyl Cyclase Inhibitors; D007074:Immunoglobulin G; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D000254:Sodium-Potassium-Exchanging ATPase