The relationship between glucose utilization during ischemia and ventricular fibrillation during early reperfusion. Evidence for two populations of guinea pig hearts.

Abstract

Guinea pig hearts perfused in the presence of 9 mM glucose were subjected to 30 min of ischemia (coronary flow reduced to 6%) and were then reperfused. During reperfusion, 18 of the 34 hearts studied (first subgroup) exhibited irreversible ventricular fibrillation. The remaining 16 hearts (second subgroup) exhibited serious rhythm disturbances but did not fibrillate. Attempts to identify critical factors that might precipitate fibrillation led to an observation that hearts that fibrillated during reperfusion were characterized by low rates of glucose utilization (0.6 +/- 0.8 mumol/min per g dry wt. and low lactate plus pyruvate production (2.5 +/- 0.32 mumol/min per g dry wt.) during ischemia. In addition, these hearts had a low calculated cytoplasmic ATP-to-ADP ratio (10.0) and low residential glycogen levels (55 +/- 7.0 mumol glucose equivalents/g dry wt.) at the end of the ischemic period. In contrast, in hearts that did not fibrillate (group 2), glucose utilization (2.5 +/- 0.12 mumol/min per g dry wt.) was higher, lactate plus pyruvate production was higher (7.4 +/- 0.03 mumol/min per g dry wt.), cytoplasmic ATP-to-ADP ratio was higher (36.0), and residual glycogen levels were higher (163 +/- 23 mumol glucose equivalents/g dry wt.). Thus, two distinct populations of guinea pig hearts were apparent, and comparison between the two groups indicated an association among glucose utilization, cytoplasmic energy status, and myocardial electrical stability.