Increased beta-oxidation of erucic acid in perfused hearts from rats fed clofibrate.

1. The metabolism of [14-14C]erucate and [U-14C]palmitate has been investigated in perfused heart from rats fed 0.3% clofibrate for 10 days and from control rats. 2. The total uptake of fatty acids in the heart increased in the clofibrate fed group. Clofibrate increased the oxidation of [14-14C]erucic acid by 100% and the oxidation of [U-14C]palmitic acid by 30% compared to controls. 3. The chain-shortening of erucate to C20:1 and C18:1 fatty acids in the perfused heart was stimulated at least two-fold by clofibrate feeding. 4. The activity of the peroxisomal marker enzyme catalase increased 60%, the activity of cytochrome oxidase increased approx. 16% and the content of total coenzyme A increased 30% in heart homogenates from rats fed clofibrate compared to controls. 5. The isolated mitochondrial fraction from clofibrate fed rats showed an increased capacity for oxidation of palmitoylcarnitine and decanoylcarnitine, while the oxidation of erucoylcarnitine showed little change. 6. It is suggested that clofibrate increases the oxidation of [14-14C]erucic acid in the perfused heart by increasing the capacity for chain-shortening of [14-14C]erucate in the peroxisomal beta-oxidation system.