title: Relaxation of frog myocardium.
abstract: Tension fall of frog heart contraction was analyzed under voltage-clamp conditions. It appears mostly exponential. The rate of relaxation depends upon the extracellular and intracellular Na concentrations. This suggests that the relaxation is under the control of Na-Ca exchange. The speeding up of relaxation by adrenaline in frog heart is revealed by low Na solution, while it is hidden by the primordial Na-Ca exchange in Ringer's solution.
mesh_terms: D000818:Animals; D001001:Anura; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism; D004837:Epinephrine / Q000494:pharmacology; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism; D011894:Rana pipiens; D012964:Sodium / Q000378:metabolism; D014702:Veratrine / Q000494:pharmacology
chemical_list: D012964:Sodium; D014702:Veratrine; D002118:Calcium; D004837:Epinephrine