The uptake of free fatty acid in the rat heart.

During the perfusion of isolated rat hearts with [1 - 14C]palmitate or [1 - 14C]oleate the rate of incorporation of label into lipids is greater in the microsomal fraction, less in the mitochondrial fraction, and least in the cell sap fraction. The degree of esterification is greatest in the microsomal fraction and greater for oleate than for palmitate. There is an early and high degree of labeling of phospholipid in the microsomal fraction. The specific activity of mitochondrial free fatty acids is higher than that of microsomal or cell sap free fatty acids.