[Relationship between anaerobic energy formation and myocardial contractile function in disturbed cardiac blood...

Graded 70 and 90% restrictions of the coronary blood flow were reproduced in dogs with closed chest upon catheterization and autoperfusion of the circumflex branch of the left coronary artery. Interrelations between shifts in anaerobic carbohydrate metabolism and the main parameters of myocardial contractility were explored. An increase in glycolytic and phosphorylase activities, lactic acid concentration and a drop in the glycogen level were disclosed. The alterations were most pronounced in the ischemic area upon 90% restriction of coronary perfusion, whereas in the left ventricular myocardium outside the ischemic area, they were less detectable. There was a significant negative correlation between the lactate level and glycolysis intensity in both the heart areas under study and the contractility rate parameters dp/dt max, Vpm. dp/dt/p, etc. Lactic acid accumulation in the ischemic myocardium is an important factor inhibiting contractility. This may be caused by acidosis as well as by the mechanisms which are independent of pH changes.