The fatty acid composition of chylomicrons influences the rate of their lipolysis in vivo.Nutr Metab Cardiovasc Dis. 2000 Jun; 10(3):121-5.NM
BACKGROUND AND AIMS
Previous work in our laboratory has shown that chylomicron triacylglycerol is lipolysed in vitro by lipoprotein lipase more rapidly when the particles are enriched with n-6 polyunsaturated as compared to saturated, monounsaturated or n-3 polyunsaturated fatty acids. It is possible, however, that this does not reflect the situation in vivo, where the active enzyme is bound to the vascular endothelium. The aim of the present study is to investigate the effect of the fatty acid composition of chylomicrons on their lipolysis in the rat in vivo.
METHODS AND RESULTS
[3H]Oleate-labelled chylomicrons derived from palm, olive, corn or fish oil (enriched in saturated, monounsaturated, n-6 polyunsaturated and n-3 polyunsaturated fatty acids respectively) containing > 90% of the label in triacylglycerol were injected intravenously into functionally hepatectomised rats and blood samples were taken at time intervals up to 40 min. The radioactivity in serum triacylglycerol decreased significantly more rapidly when corn oil as compared to palm, olive or fish oil chylomicrons were used. Conversely, the radioactivity in serum free fatty acid derived from corn oil chylomicrons showed a faster increase than that derived from the other three types of particles.
These results indicate that chylomicrons enriched with n-6 polyunsaturated fatty acids are converted to chylomicron remnants in vivo more rapidly than those enriched with saturated, monounsaturated or n-3 polyunsaturated fatty acids. This provides a partial explanation for the differential rate of removal from the blood of cholesterol carried in chylomicrons of different fatty acid composition demonstrated in previous work from this laboratory.