The overdosis of intermediate products of citric acid cycle caused the ST・T abnormalities and prolongation of Q-Tc in normal dogs. Sodium citrate gave the greatest influence upon the ECG and sodium succinate showed the weakest effect upon ST・T. The ST depressions caused by droplet injection of sodium pyruvate were improved by ATP, TDP and AMP. The direct epicardial lead ECG showed that the small amount of pyruvate improved the ST・T and the overdosis aggravated the ST・T abnormalities. The relationship between the ST・T changes and metabolic disturbance of citric acid cycle was discussed.