Studies on the in vivo synthesis of triacylglycerol in mouse liver.
The in vivo biosynthesis of hepatic glycerolipids was examined by studying the incorporation of [2-3H] glycerol into triacylglycerol in the mouse. The isotope was administered by rapid injection into the portal vein. The incorporation of glycerol was linear for about 1 min and maximal rates were seen in the presence of additional oleic acid. At 20 mumol of oleic acid bound to 1 mumol of bovine serum albumin, the highest level tested, glycerol incorporation was still increasing linearly, whereas a plateau was reached at 4 mumol of glycerol. The liver incorporated 200-300 nmol of [2-3H] glycerol into triacyglycerol per min when 20 mumol of albumin-bound oleic acid plus 4 mumol of glycerol were injected in a 0.2 ml volume. Studies on the uptake by the liver after intraportal injection revealed that at 0.5 min the liver retained 2 mumol of glycerol and 5 mumol of oleic acid, indicating that the uptake of substrate was not rate-limiting. The results suggest that the availability of substrate is a major factor in the regulation of triacyglycerol biosynthesis by the liver.
D000818:Animals; D002250:Carbon Radioisotopes; D005990:Glycerol / Q000378:metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D019787:Linoleic Acid; D008041:Linoleic Acids / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008297:Male; D051379:Mice; D008808:Mice, Inbred CBA; D019301:Oleic Acid; D009829:Oleic Acids / Q000378:metabolism; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000378:metabolism; D014280:Triglycerides / Q000096:biosynthesis*; D014316:Tritium
D002250:Carbon Radioisotopes; D008041:Linoleic Acids; D009829:Oleic Acids; D010169:Palmitic Acids; D014280:Triglycerides; D014316:Tritium; D019301:Oleic Acid; D019308:Palmitic Acid; D019787:Linoleic Acid; D005990:Glycerol