Effects of arterial hypoxemia and splenic nerve stimulation on myocardial adenosine 3',5'-Monophosphate in dogs.
Epinephrine infusion, 5-percent oxygen breathing, and splenic nerve stimulation were employed to increase cardiac output by 50-100% in anesthetized dogs. Epinephrine infusion as expected, increased plasma and myocardial cyclic AMP concentrations. Arterial hypoxemia increased cyclic AMP concentration in plasma but not in the heart. Practolol pretreatment abolished the increase in plasma cyclic AMP concentration and reduced the rise in cardiac output during hypoxemia. Splenic nerve stimulation was not associated with increases in either plasma or myocardial cyclic AMP. Adenylate cyclase activity was increased by addition of plasma into the incubation medium. However, splenic venous plasma obtained during splenic nerve stimulation  did not increase adenylate cyclase activity more than control plasma obtained before stimulation. We conclude that the positive inotropic action of arterial hypoxemia and splenic nerve stimulation does not depend on the adenylate cyclase-cyclic AMP system.
D000262:Adenylyl Cyclases / Q000097:blood / Q000378:metabolism; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D000242:Cyclic AMP / Q000097:blood / Q000378:metabolism*; D003864:Depression, Chemical; D004285:Dogs; D004558:Electric Stimulation; D004837:Epinephrine / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects; D000860:Hypoxia / Q000097:blood / Q000378:metabolism*; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism*; D011217:Practolol / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D013154:Spleen / Q000098:blood supply / Q000294:innervation*; D013268:Stimulation, Chemical; D013564:Sympathetic Nervous System / Q000502:physiology
D011433:Propranolol; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D011217:Practolol; D004837:Epinephrine