Acute changes in high energy phosphates, nucleotide derivatives, and contractile force in ischaemic and nonischaemic canine myocardium following coronary occlusion.

Studies of ischaemic myocardium following occlusion of coronary arterial branches revealed a substantial decline in creatine phosphate, adenosine triphosphate, and total adenine nucleotide contents over 40 min. Contents of nucleotide breakdown derivatives increased significantly but transiently. Contractile force declined rapidly and stabilized at a low level. In nonischaemic muscle following occlusion creatine phosphate, adenosine triphosphate, and total nucleotide contents declined rapidly, although not to the degree seen in ischaemic muscle. Contents of derivatives increased only slightly. Contractile force increased.