Distribution of apolipoproteins A-I and A-IV among lipoprotein classes in rat mesenteric lymph, fractionated by molecular sieve chromatography.
The distribution of apolipoproteins A-I and A-IV among lymph lipoprotein fractions was studied after separation by molecular sieve chromatography, avoiding any ultracentrifugation. Lymph was obtained from rats infused either with a glucose solution or with a triacylglycerol emulsion. Relative to glucose infusion, triacylglycerol infusion caused a 20-fold increase in the output of triacylglycerol, coupled with a 4-fold increase in output of apolipoprotein A-IV. The output of apolipoprotein A-I was only elevated 2-fold. Chromatography on 6% agarose showed that lymph apolipoproteins A-I and A-IV are present on triacylglycerol-rich particles and on particles of the size of HDL. In addition, apolipoprotein A-IV is also present as 'free' apolipoprotein A-IV. The increase in apolipoprotein A-I output is caused by a higher output of A-I associated with large chylomicrons only, while the increase in apolipoprotein A-IV output is reflected by an increased output in all lymph lipoprotein fractions, including lymph HDL and 'free' apolipoprotein A-IV. The increased level of 'free' A-IV, seen in fatty lymph, may contribute to, and at least partly explain, the high concentrations of 'free' apolipoprotein A-IV present in serum obtained from fed animals.
Dallinga-Thie
G M
GM
van Tol
A
A
van't Hooft
F M
FM
Groot
P H
PH
D000042:Absorption; D000818:Animals; D016632:Apolipoprotein A-I; D001053:Apolipoproteins / Q000378:metabolism; D001054:Apolipoproteins A / Q000032:analysis*; D001692:Biological Transport; D002850:Chromatography, Gel; D002914:Chylomicrons / Q000032:analysis; D005947:Glucose / Q000378:metabolism; D050356:Lipid Metabolism; D008196:Lymph / Q000032:analysis*; D008297:Male; D008643:Mesentery / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D014280:Triglycerides / Q000378:metabolism
D016632:Apolipoprotein A-I; D001053:Apolipoproteins; D001054:Apolipoproteins A; D002914:Chylomicrons; D014280:Triglycerides; C022205:apolipoprotein A-IV; D005947:Glucose