Muscarinic stimulation of cardiac guanylate cyclase.
Right ventricular kitten papillary muscles were incubated with dibutyryl adenosine 3',5'-monophosphate (db-cAMP) at varying concentrations from 1 X 10(-4) M to 1 X 10(-3) M. A positive inotropic effect was observed with all concentrations of db-cAMP. Concomitant administration of 5 X 10(-4) M monobutyryl guanosine 3',5'-monophosphate and 1--2 X 10(-4) M db-cAMP did not produce an inotropic response. At the biochemical level cardiac guanyl cyclase activity is enhanced 2--3 times with acetylcholine and this enhancement is completely blocked by atropine. This increased activity appears to be the result of a decrease in the Michaelis constant (Km) for GTP. Calcium also produces a significant activation of guanyl cyclase activity.
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D001285:Atropine / Q000494:pharmacology*; D003994:Bucladesine / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology; D002415:Cats; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D006162:Guanylate Cyclase / Q000378:metabolism*; D006321:Heart / Q000187:drug effects; D007700:Kinetics; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000201:enzymology*; D051381:Rats
D003994:Bucladesine; D001285:Atropine; D006162:Guanylate Cyclase; D006152:Cyclic GMP; D000109:Acetylcholine; D002118:Calcium