title: On the metabolism of lipoprotein-X (LP-X).
abstract: The characteristic low-density lipoprotein of cholestasis (LP-X) earlier described for humans is found with identical properties in dogs and rats after experimental cholestasis. After ligation of the common bile duct, LP-X may be detected in the plasma within the first 20 hours. A period of marked increase in concentration is followed by decreasing plasma concentrations and LP-X becomes undetectable 7-10 days after ligation of the bile duct in rats. High plasma bile salt concentration may alter the structural integrity of LP-X and may in part be responsible for its disappearance after long-lasting and severe biliary obstruction. Plasma decay curves for isolated LP-X injected intravenously into healthy animals revealed a rapid early fall in concentration followed by a gradual decline. The calculated fractional catabolic rate of LP-X was found to be 0.450 +/- 0.069 for dogs and 1.553 +/- 0.096 for rats corresponding to a mean biological half life of 37.7 +/- 6.4 h or 10.7 +/- 0.6 h, respectively. In vitro LP-X degradation occurs in post-heparin plasma, however, it seems to be too early to speculate on the enzyme activity and on the mode of action responsible for this disappearance.
mesh_terms: D000818:Animals; D001652:Bile Ducts / Q000502:physiology; D004285:Dogs; D005260:Female; D006801:Humans; D007122:Immunoelectrophoresis; D007728:Kupffer Cells / Q000378:metabolism; D008079:Lipoproteins, VLDL / Q000097:blood / Q000378:metabolism*; D008099:Liver / Q000166:cytology / Q000378:metabolism; D008297:Male; D051381:Rats; D013045:Species Specificity
chemical_list: D008079:Lipoproteins, VLDL