Dichloroacetate enhanced myocardial functional recovery post-ischemia: ATP and NADH recovery

This study was undertaken to determine the effect of dichloroacetate (DCA) on myocardial functional and metabolic recovery following global ischemia. Isolated rabbit hearts were subjected to 120 min of mildly hypothermic (34°C), cardioplegic arrest with multidose, modified St. Thomas' cardioplegia. Hearts were reperfused with either physiologic salt solution (PSS) as controls, (CON, n = 10) or PSS containing DCA (DCA, n = 6) at a concentration of 1 mM. Functional and metabolic indices were determined at baseline and at 15, 30, and 45 min of reperfusion. In four DCA and four CON hearts, myocardial biopsies were taken at baseline, end-ischemia, 15 and 45 min for nucleotide levels. Functional recovery was significantly better in hearts reperfused with DCA as demonstrated by recovery of baseline developed pressure (DCA = 69 ± 5%, CON = 45 ± 9%) and dP/dt (DCA = 64% ± 10% versus CON = 48% ± 10%). Coronary blood flow was not different between groups either at baseline or during reperfusion, but myocardial oxygen consumption (MVO₂) was increased in the DCA versus CON hearts (79% ± 20% of baseline vs 50% ± 18%). Recovery of myocardial adenylate energy status was improved in the DCA versus CON hearts (ATP recovered to 45% ± 20% versus 8% ± 6% of baseline). Coronary sinus lactate concentration was decreased in DCA perfused hearts at 45 min of reperfusion. Percent of baseline NADH values was similar at 15 min of reperfusion, but at 45 min, DCA hearts showed a decrease in NADH levels, while CON hearts showed an increase (DCA = 48%; CON = 121%). The enhanced myocardial function and improved metabolic status noted with DCA may result from increased oxidative phosphorylation due to altered pyruvate dehydrogenase (PDH) activity.