Abstract
The ability of several drugs to restore directly elicited twitches of the rat diaphragm depressed by excess potassium chloride has been studied. The drugs found to be effective were sympathomimetic amines, insulin, glucagon, caffeine, theophylline, calcium chloride and hexosephosphates. The effects of the sympathomimetic amines and glucagon were blocked by beta-receptor blocking agents. Phloridzin blocked the effect of insulin and depressed that of glucagon. The increase in twitch tension still occurred under anaerobic conditions and was not abolished by the glycolytic inhibitor, iodoacetate. All of the effective drugs are known to affect carbohydrate metabolism and the suggestion by Ellis (1955) that the effect on contractions may be a result of increased intracellular hexosephosphate levels is discussed.