The effect of added monoacylglycerols on the removal from plasma of chylomicron-like emulsions injected intravenously in rats.
Lipid emulsions were prepared with compositions similar to the triacylglycerol-rich plasma lipoproteins, but also incorporating added small amounts of monoacylglycerols. Control emulsions without monoacylglycerol were metabolized similarly to natural chylomicrons or very-low-density lipoproteins when injected intravenously in rats. The emulsion triacylglycerols and cholesteryl esters were both removed rapidly from the bloodstream, with the removal rates of triacylglycerols faster than those of cholesteryl esters. Much of the removed cholesteryl ester was found in the liver, but only a small fraction of the triacylglycerol, consistent with hepatic uptake of the triacylglycerol-depleted remnants of the injected emulsion. Emulsions incorporating added monooleoylglycerol or stearic acid were metabolized similarly. Added 1- or 2-monostearoylglycerol had no effect on triacylglycerol removal from plasma, but the removal rate of cholesteryl esters was decreased and less cholesteryl ester was found in the liver. These effects are similar to those recently described when emulsions and chylomicrons contained triacylglycerols with a saturated acyl chain at the glycerol 2-position, suggesting that saturated monoacylglycerol produced by the action of lipoprotein lipase may cause triacylglycerol-depleted remnant particles to remain in the plasma instead of being rapidly taken up by the liver.
Mortimer
B C
BC
Department of Physiology, University of Western Australia, Nedlands.
Simmonds
W J
WJ
Joll
C A
CA
Stick
R V
RV
Redgrave
T G
TG
D000818:Animals; D002788:Cholesterol Esters / Q000493:pharmacokinetics; D002914:Chylomicrons / Q000493:pharmacokinetics*; D004655:Emulsions / Q000493:pharmacokinetics*; D005989:Glycerides / Q000493:pharmacokinetics / Q000494:pharmacology*; D008066:Lipolysis / Q000187:drug effects; D008079:Lipoproteins, VLDL / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013229:Stearic Acids / Q000493:pharmacokinetics; D014280:Triglycerides / Q000493:pharmacokinetics
D002788:Cholesterol Esters; D002914:Chylomicrons; D004655:Emulsions; D005989:Glycerides; D008079:Lipoproteins, VLDL; D013229:Stearic Acids; D014280:Triglycerides; C031183:stearic acid; C005953:monoolein