Comparative study of chylomicron and fatty acid utilization in small intestine and heart.

Chylomicrons were isolated from the urine of rats after a surgical procedure in which the cysterna chyli was connected with the right ureter. The fatty acids of the chylomicrons served as a respiratory substrate for rat heart and not for rat small intestine during in vitro vascular perfusions. The reason for the absence of chylomicron utilization in small intestine was found to be the virtual absence of lipoprotein lipase from this organ. Both heart and small intestine oxidized oleate complexed to albumin. Increasing the molar ratio of fatty acid to albumin from 3 to 6 did not affect the rate of fatty acid oxidation in heart, but increased fatty acid oxidation in small intestine.