The effects of metabolic inhibition on intracellular pH and Ca.

We have investigated the effects of inhibiting aerobic and/or anaerobic metabolism on contraction, intracellular calcium and pH in single rat ventricular myocytes. Inhibition of aerobic metabolism alone (with CN) had little effect on these variables. However, if anaerobic glycolysis was also inhibited, then the application of CN decreased systolic [Ca2+]i and increased diastolic [Ca2+]i. There was also a development of a diastolic contracture which lagged behind the increase of diastolic [Ca2+]i. These events were accompanied by an intracellular acidosis. The acidosis was shown to depress contraction and perhaps to account for the fact that diastolic [Ca2+]i increased before the contracture.