Metabolism of apolipoproteins C-II, C-III, and B in hypertriglyceridemic men. Changes after heparin-induced lipolysis.
The C apolipoproteins are normally transferred to high density lipoproteins (HDL) after lipolysis of very low density lipoprotein (VLDL) triglyceride. In previous studies, a loss of plasma C apolipoproteins was documented after heparin-induced lipolysis in hypertriglyceridemic subjects. The present studies were designed to determine if this decline in plasma C apolipoproteins was due to their clearance with VLDL remnants. Five Type IV hypertriglyceridemic and two normal subjects were injected with 125I-VLDL and 131I-low density lipoproteins (LDL) to document kinetically an excess of VLDL apolipoprotein (apo) B flux relative to LDL apo B flux in the Type IV subjects. A mean of 46% VLDL apo B was cleared from the circulation, without conversion to intermediate density lipoprotein (IDL) or LDL. Heparin was then infused (9000 IU over 4 hours) to generate an excess of VLDL remnants that were not converted to IDL or LDL. VLDL triglyceride, apo B, and apo C concentrations fell at a similar rate. VLDL apo B declined by 42% (p less than 0.01). However, no increases were observed in IDL or LDL apo B in the Type IV subjects. This resulted in a 14% (p less than 0.01) decline in plasma apo B concentrations, indicating a clearance of VLDL remnants. VLDL apo C-II and C-III concentrations fell by 42% (p less than 0.025) and 52% (p less than 0.01), respectively. During the first 2.5 hours of infusion, they were almost quantitatively recovered in HDL. Thereafter, the C apolipoproteins declined in HDL during which time VLDL apo C concentrations continued to decline.(ABSTRACT TRUNCATED AT 250 WORDS)
Huff
M W
MW
Department of Medicine, University Hospital, University of Western Ontario, London, Canada.
Breckenridge
W C
WC
Strong
W L
WL
Wolfe
B M
BM
D000328:Adult; D053304:Apolipoprotein C-II; D053305:Apolipoprotein C-III; D001055:Apolipoproteins B / Q000097:blood*; D001056:Apolipoproteins C / Q000097:blood*; D006493:Heparin / Q000494:pharmacology; D006801:Humans; D006953:Hyperlipoproteinemia Type IV / Q000097:blood*; D007457:Iodine Radioisotopes; D007700:Kinetics; D008066:Lipolysis / Q000187:drug effects*; D008074:Lipoproteins / Q000097:blood; D053419:Lipoproteins, IDL; D008077:Lipoproteins, LDL / Q000097:blood; D008079:Lipoproteins, VLDL / Q000097:blood; D008297:Male; D008875:Middle Aged
D053304:Apolipoprotein C-II; D053305:Apolipoprotein C-III; D001055:Apolipoproteins B; D001056:Apolipoproteins C; D007457:Iodine Radioisotopes; D008074:Lipoproteins; D053419:Lipoproteins, IDL; D008077:Lipoproteins, LDL; D008079:Lipoproteins, VLDL; D006493:Heparin