Stimulation of Na+ pump in cardiac myocytes and intact ventricles by low doses of digitaloids is independent of beta-adrenergic stimulation.
In isolated cardiac myocytes from adult rats low concentrations of ouabain, 10(-9) to 5 X 10(-10) M, decreased cellular Na+ content and 45Ca influx and increased 86Rb uptake. Propranolol, 10(-7) M, did not affect these parameters either in the presence or absence of ouabain. These results indicate that Na+ pump stimulation by low concentrations of digitaloids may occur in the absence of adrenergic innervation and is unaffected by adrenergic beta-blockade. Stimulation of 86Rb uptake in ventricular muscle slices was also unaffected by propranolol, indicating that in intact ventricular muscle also, the effect does not depend on beta-adrenergic mediation. This is in contrast to earlier reports on studies in isolated atria.
D000818:Animals; D002118:Calcium / Q000378:metabolism; D006352:Heart Ventricles / Q000378:metabolism*; D007473:Ion Channels / Q000378:metabolism*; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D010042:Ouabain / Q000378:metabolism / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism; D011433:Propranolol / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012413:Rubidium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*
D007473:Ion Channels; D010042:Ouabain; D012964:Sodium; D011433:Propranolol; D012413:Rubidium; D011188:Potassium; D002118:Calcium