The most important immediate source of energy in cardiac muscle is that imparted from phosphate bonds. Previous studies using human myocardium indicated that a number of nucleotides may provide this chemical reservoir of energy and that the adenosine nucleotides represent the greatest contribution.7 Changes in these compounds (adenosine monophosphate [AMP], adenosine diphosphate [ADP], and adenosine triphosphate [ATP]) have been followed in the canine myocardium during induced cardiac arrest, with special attention being given to the recovery phase following arrest.
Method
The heart of one animal was isolated and perfused by connecting it to the circulatory system of another animal, passing blood from the right femoral artery to the brachiocephalic artery of the isolated heart and returning it to the left femoral vein.15 Heparin was used to prevent clotting, coronary flow was maintained at 5 ml. per kilogram body weight per minute, and temperature was carefully controlled by means