Influence of exercise on chylomicron triacylglycerol metabolism: plasma turnover and muscle uptake.
Triacylglycerides (TG), circulating in chylomicrons, represent a potentially rich source of plasma substrates available for tissue uptake. Chylomicron TG are first hydrolyzed by the action of lipoprotein lipase prior to tissue uptake of the TG-derived fatty acids. Although the removal of these TG by fat cells appears to favor a storage function, uptake by skeletal muscle accounts for a significant portion of the TG removed from plasma. Further, uptake of TG-derived fatty acids by skeletal muscle is increased during exercise. This could contribute to an increased rate constant for TG removal from the plasma during exercise. A significant portion of the TG-derived fatty acids that enter muscle during exercise remain in the non-esterified fatty acid pool of the muscle where they could provide a substrate for beta-oxidation. Indirect estimates of the contribution that TG-derived fatty acids may make to the total energy costs during exercise in a fasting condition may be minor. However, appropriate direct measurements during a postprandial condition, where total plasma TG turnover is very large, have not been made.
D000818:Animals; D002914:Chylomicrons / Q000378:metabolism*; D004285:Dogs; D005215:Fasting; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D008071:Lipoprotein Lipase / Q000378:metabolism; D008079:Lipoproteins, VLDL / Q000378:metabolism; D009132:Muscles / Q000378:metabolism*; D010084:Oxidation-Reduction; D005082:Physical Exertion; D051381:Rats; D014280:Triglycerides / Q000378:metabolism
D002914:Chylomicrons; D005230:Fatty Acids, Nonesterified; D008079:Lipoproteins, VLDL; D014280:Triglycerides; D008071:Lipoprotein Lipase