[Phase action of ouabain on the electrical and contractile activity of the frog myocardium].
Ouabain effects (5 X 10(-8)-5 X 10(-5) M) on the isometric contraction and intracellular action potentials were studied on frog atrial and ventricular muscles. It was found that ouabain produced a three-phase action on the electrical and contractile activity of the myocardium under different patterns of stimulation both in normal Ringer and D-600-containing solutions. The data suggest that the three-phase ouabain action is a consequence of its influence on at least two component processes of the excitation-contraction coupling in the frog heart muscle: the slow Na-Ca channels of the sarcolemma and Na+-K+ pump. The contribution of each mechanism depends on the glycoside concentration and the duration of exposure to ouabain.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D004305:Dose-Response Relationship, Drug; D006321:Heart / Q000187:drug effects*; D006325:Heart Atria / Q000187:drug effects; D006352:Heart Ventricles / Q000187:drug effects; D007473:Ion Channels / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000378:metabolism; D010042:Ouabain / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism; D011896:Rana temporaria; D012964:Sodium / Q000378:metabolism
D007473:Ion Channels; D010042:Ouabain; D012964:Sodium; D011188:Potassium
Fazovoe deĭstvie ouabaina na élektricheskuiu i sokratitel'nuiu aktivnost' miokarda liagushki.