title: CALCIUM IN RELATION TO THE ACTIONS OF OUABAIN AND ADRENALINE ON THE HEART.
abstract: Isolated pairs of rabbit auricles have been observed in media containing 6, 24 or 75 mM-potassium, with corresponding reductions in sodium concentration. In 24 mM-potassium, adrenaline restored beating and excitability, as did calcium chloride, but ouabain had no effect. In 75 mM-potassium, adrenaline had no effect; calcium chloride caused a contracture; ouabain had no direct effect, but auricles which had been beating in the presence of ouabain contracted promptly on transfer to 75 mM-potassium. Left auricles, which do not beat spontaneously, were less sensitive to calcium and to ouabain. The results showed a membrane stabilizing action of calcium and an action on muscular contraction, and suggested that cardiac glycosides acted by causing accumulation of calcium at the activator site in the tissue.
mesh_terms: D000818:Animals; D002110:Caffeine; D002118:Calcium; D002122:Calcium Chloride; D002136:Calcium, Dietary; D002301:Cardiac Glycosides; D004837:Epinephrine; D006321:Heart; D000860:Hypoxia; D008660:Metabolism; D009119:Muscle Contraction; D010042:Ouabain; D010600:Pharmacology; D011188:Potassium; D011817:Rabbits; D012106:Research; D012964:Sodium
chemical_list: D002136:Calcium, Dietary; D002301:Cardiac Glycosides; D002110:Caffeine; D010042:Ouabain; D012964:Sodium; D002122:Calcium Chloride; D011188:Potassium; D002118:Calcium; D004837:Epinephrine
keywords: ANOXIA; CAFFEINE; CALCIUM; EPINEPHRINE; EXPERIMENTAL LAB STUDY; HEART; METABOLISM; OUABAIN; PHARMACOLOGY; POTASSIUM; RABBITS; SODIUM