The effect of anions and cations on cardiac adenylate cyclase: interactions with isoprenaline and GTP.
Anions stimulated rabbit heart adenylate cyclase in the order chloride greater than phosphate greater than acetate, while the cations sodium and potassium had little effect. Activation by KCI was multiplicative with that of fluoride. Isoprenaline (10(-4) M) and GTP(10(-4) M) stimulated the cyclase independently, and their combined effects were multiplicative. GTP stimulated less than chloride but more than acetate. Activation by chloride or acetate was more than additive with that by GTP. The effect of isoprenaline was reduced in the presence of chloride or acetate, and this reduction was not modified by sodium or potassium. It was concluded that ionic influence may be biologically important in modifying cyclase activity and the extent of beta-receptor stimulation.
D000085:Acetates / Q000494:pharmacology; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D000838:Anions; D002412:Cations; D002712:Chlorides / Q000494:pharmacology; D004789:Enzyme Activation; D006160:Guanosine Triphosphate / Q000494:pharmacology*; D007545:Isoproterenol / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D009206:Myocardium / Q000201:enzymology*; D010710:Phosphates / Q000494:pharmacology; D011817:Rabbits; D012508:Sarcolemma / Q000201:enzymology*
D000085:Acetates; D000838:Anions; D002412:Cations; D002712:Chlorides; D010710:Phosphates; D006160:Guanosine Triphosphate; D000262:Adenylyl Cyclases; D007545:Isoproterenol