Regulation of guinea pig very low density lipoprotein secretion rates by dietary fat saturation.
We investigated the effects of dietary fat saturation on very low density lipoprotein (VLDL) production in guinea pigs fed semipurified diets containing 15% (w/w) fat, either corn oil (CO, 58% linoleic acid), lard (LA, 42% oleic and 24% palmitic acids) or palm kernel oil (PK, 52% lauric and 18% myristic acids) for 4 weeks. Animals were given an intravenous injection of Triton WR 1339 to block VLDL catabolism and rates of VLDL triacylglycerol (TAG) and apolipoprotein (apo) B secretion were measured over time. Plasma TAG concentrations increased linearly for 8 h (r = 0.99) and VLDL-TAG secretion rates were significantly higher (P < 0.01) in guinea pigs fed LA (72.7 +/- 14.7 mg/kg-h, n = 12) compared to animals fed PK (55.4 +/- 13.4 mg/kg-h, n = 12) or CO (48.6 +/- 17.5 mg/kg-h, n = 15). VLDL apoB secretion rates were highest in PK-fed animals (3.1 +/- 1.8 mg/kg-h) compared to guinea pigs fed LA (1.5 +/- 0.8 mg/kg-h) or CO (1.1 +/- 0.6 mg/kg-h) diets (P < 0.005). Concurrent with analysis of VLDL secretion, turnover of 125I-labeled LDL was measured. Low density lipoprotein (LDL) fractional catabolic rates were not altered by Triton treatment and LDL apoB specific radioactivity (cpm/microgram) did not change over time indicating that: a) the Triton blockage of VLDL catabolism was complete, and b) there was no direct secretion of LDL by the liver. These data demonstrate that intake of lard increases the rate of VLDL-triacylglycerol secretion and that nascent VLDL particles from the lard and corn oil diet groups have the same relative triacylglycerol content, whereas palm kernel oil intake increases secretion of VLDL particles which have a reduced triacylglycerol content. These results demonstrate that dietary fat chain length and saturation have specific effects on VLDL secretion rates affecting both particle number and composition.
Abdel-Fattah
G
G
Department of Nutritional Sciences, University of Arizona, Tucson 85721, USA.
Fernandez
M L
ML
McNamara
D J
DJ
D000818:Animals; D001055:Apolipoproteins B / Q000378:metabolism; D003314:Corn Oil; D004041:Dietary Fats / Q000008:administration & dosage*; D006168:Guinea Pigs; D007850:Lauric Acids / Q000008:administration & dosage; D019787:Linoleic Acid; D008041:Linoleic Acids / Q000008:administration & dosage; D008079:Lipoproteins, VLDL / Q000378:metabolism*; D008297:Male; D019814:Myristic Acid; D009227:Myristic Acids / Q000008:administration & dosage; D019301:Oleic Acid; D009829:Oleic Acids / Q000008:administration & dosage; D011092:Polyethylene Glycols / Q000494:pharmacology; D014280:Triglycerides / Q000378:metabolism; D015430:Weight Gain
D001055:Apolipoproteins B; D004041:Dietary Fats; D007850:Lauric Acids; D008041:Linoleic Acids; D008079:Lipoproteins, VLDL; D009227:Myristic Acids; D009829:Oleic Acids; D014280:Triglycerides; D019814:Myristic Acid; C030358:lauric acid; D019301:Oleic Acid; D011092:Polyethylene Glycols; D003314:Corn Oil; D019787:Linoleic Acid; C029310:lard; C016811:tyloxapol