The sequence and correlation of the changes in several parameters of energy metabolism induced by ischemic insult in heart muscle.

Samples of myocardium with varying degrees of ischemia were obtained from subendo- and subepicardium of nonischemic, ischemic border and center zones of canine left ventricles to assess the sequence of rapid alterations of several parameters of energy metabolism induced by myocardial ischemia. Ischemia was induced by occluding the left anterior descending coronary artery. The contents of creatine phosphate (CP) and ATP decreased significantly. There was a significant accumulation of lactate. The redox potential (Eh) and phosphorylation potential (l') also decreased sharply, but only a slight decrease in energy charge (E.C.) was noted. A close correlation was found between ATP and total adenine nucleotide (r = 0.99). There were various degrees of linear correlation between other parameters, except for ATP (and total adenine nucleotide) and Pi, and CP and l', which were uncorrelated. The sequence of rapid alterations in the parameters of energy metabolism induced by ischemia was: (1) l' and CP, (2) Pi, ATP and Eh, and finally (3) lactate and E.C. A significant increase of the heart rate and a decline of the mean blood pressure and left ventricular pressure (LVP) were also observed in association with a slight change in the maximum rate of rise of the left ventricular pressure (dP/dtmax).