title: The membrane potential modulates the ATP-dependent Ca2+ pump of cardiac sarcolemma.
abstract: The effect of membrane potential on the activity of the ATP-dependent Ca2+ pump of isolated canine ventricular sarcolemmal vesicles was investigated. The membrane potential was controlled by the intravesicular and extravesicular concentration of K+, and the initial rates of Ca2+ uptake both in the presence and the absence of valinomycin were determined. The rate of Ca2+ uptake was stimulated by a inside-negative potential induced in the presence of valinomycin. The valinomycin-dependent stimulation was enhanced by the addition of K+ channel blocker, tetraethylammonium ion or Ba2+. The electrogenicity of cardiac sarcolemmal ATP-dependent Ca2+ pump is suggested from the increase of Ca2+ uptake by negative potential induced by valinomycin.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D001464:Barium / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D004285:Dogs; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D008564:Membrane Potentials; D009206:Myocardium / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism / Q000494:pharmacology; D011817:Rabbits; D012508:Sarcolemma / Q000378:metabolism*; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D014634:Valinomycin / Q000494:pharmacology
chemical_list: D007473:Ion Channels; D013757:Tetraethylammonium Compounds; D014634:Valinomycin; D001464:Barium; D019789:Tetraethylammonium; D000255:Adenosine Triphosphate; D011188:Potassium; D002118:Calcium