Coenzyme A degradation in the heart: effects of diabetes and insulin.

Coenzyme A (CoA) degradation was studied in isolated working hearts from acutely diabetic rats (48 h). Hearts from diabetic rats had elevated levels of total CoA (752 +/- 15 nmol/g dry) compared to control (537 +/- 14 nmol/g dry). When hearts from diabetic animals were perfused for 5 mins with perfusate containing pyruvate, (5 mM) and glucose (11 mM) CoA levels remained unchanged. Addition of palmitate, (1.2 mM) and glucose (11 mM) to the perfusate, however, resulted in a rapid drop in CoA levels to 672 +/- 19 nmol/g dry. Palmitate had no effect on CoA levels in control hearts which did not have elevated levels of CoA. Addition of insulin to the buffer containing glucose and palmitate prevented the decrease in CoA levels in diabetic hearts. The level of long chain acyl CoA in diabetic hearts perfused with pyruvate was 105 +/- 11 nmol/g dry, and did not change when insulin was present in the perfusate. In the presence of palmitate, levels of long chain acyl CoA increased from 76 +/- 16 to 149 +/- 13 nmol/g dry, and, in this case, addition of insulin caused a further increase to 192 +/- 18 nmol/g dry. Thus, the lower rate of CoA degradation in the presence of insulin was associated with a rise in long chain acyl CoA levels. In a separate series of experiments, CoA levels were increased in control hearts in vitro (from 537 +/- 14 to 842 +/- 19 nmol/g dry). Subsequent perfusion of these hearts that contained elevated CoA with palmitate also resulted in a rapid drop of CoA to 655 +/- 17 nmol/g dry.(ABSTRACT TRUNCATED AT 250 WORDS)