Metabolism of apoprotein B in cynomolgus monkey: evidence for independent production of low-density lipoprotein apoprotein B.
The catabolism of very-low-density lipoprotein apoprotein B and its conversion to low-density lipoprotein was studied in five chow-fed cynomolgus monkeys following injection of radioiodinated homologous very-low-density lipoproteins. The mean (+/- SD) fractional catabolic rate of very-low-density lipoprotein apoprotein B was 0.97 +/- 0.20 h-1 and the mean (+/- SD) production rate was 0.76 +/- 0.20 mg X kg-1 X h-1. The percent of conversion of very-low-density lipoprotein apoprotein B to low-density lipoprotein ranged from 33 to 59%. In separate studies of low-density lipoprotein apoprotein B turnover performed using homologous radiolabeled low-density lipoprotein in five additional animals, the mean (+/- SD) fractional catabolic rate for low-density lipoprotein apoprotein B was 0.050 +/- 0.017 h-1 and the mean (+/- SD) apoprotein B production rate was 0.70 +/- 0.18 mg X kg-1 X h-1. Comparison of the total low-density lipoprotein apoprotein B production with that derived from very-low-density lipoprotein apoprotein B suggested that a large fraction of plasma low-density lipoprotein apoprotein B was derived from a source exclusive of circulating very-low-density lipoprotein apoprotein B. This was confirmed in two animals by simultaneous injection of radiolabeled very-low-density and low-density lipoproteins. Thus, a significant proportion of cynomolgus monkey low-density lipoproteins are produced either by direct hepatic secretion or by rapid conversion of lower-density lipoproteins before they appear in the peripheral circulation.
D000818:Animals; D001053:Apolipoproteins / Q000097:blood*; D001055:Apolipoproteins B; D002784:Cholesterol / Q000097:blood; D005260:Female; D007700:Kinetics; D008075:Lipoproteins, HDL / Q000097:blood; D008077:Lipoproteins, LDL / Q000097:blood*; D008079:Lipoproteins, VLDL / Q000097:blood; D008252:Macaca fascicularis; D008297:Male; D008433:Mathematics; D008954:Models, Biological; D014280:Triglycerides / Q000097:blood
D001053:Apolipoproteins; D001055:Apolipoproteins B; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D008079:Lipoproteins, VLDL; D014280:Triglycerides; D002784:Cholesterol