Effect of calcium concentration, isoproterenol, and McN-2165 on fetal rat heart rate and cyclic AMP level.
The fetal rat heart in organ culture was used to study the interaction of calcium with the cardioactive agents. McN-2165 is an agent that produces negative chronotropism and elevation in cyclic AMP levels in this preparation. A concentration of 2.76 mM calcium ion antagonized the negative chronotropic action and prevented the cyclic AMP elevation produced by this agent. Positive chronotropic actions of isoproterenol were prevented by decreasing the calcium level below 1.84 mM.
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D000242:Cyclic AMP / Q000378:metabolism*; D004347:Drug Interactions; D005260:Female; D005333:Fetus / Q000502:physiology*; D006339:Heart Rate / Q000187:drug effects*; D007545:Isoproterenol / Q000494:pharmacology*; D009206:Myocardium / Q000378:metabolism*; D011247:Pregnancy; D051381:Rats; D013843:Thiazines / Q000494:pharmacology*
D013843:Thiazines; D000242:Cyclic AMP; D007545:Isoproterenol; D002118:Calcium