Effects of lipid administration on lymphatic apolipoprotein A-IV and B output and synthesis.
We examined the mesenteric lymphatic and portal venous transport of triglyceride (TG), free fatty acids (FFA), apolipoproteins (apo)A-IV and B in response to a bolus duodenal infusion of a TG-free control solution, and long-chain (18:1) and medium-chain (8:0) TG (LCT and MCT, respectively) emulsions in the rat. Additionally, intestinal and hepatic apo A-IV and apo B mRNA levels were also measured. Lymph apo A-IV, apo B (B-48), FFA, and TG output increased after LCT infusion, whereas only apo A-IV and FFA outputs increased after MCT infusion. On the other hand, portal FFA and apo A-IV transports increased at 15 min after MCT infusion but not after LCT infusion. Portal TG and apo B transports were not altered by either MCT or LCT infusion. Jejunal apo A-IV mRNA was increased after both MCT and LCT infusions. Hepatic apo A-IV mRNA levels increased only after MCT infusion. Conversely, neither LCT nor MCT had any effect on apo B mRNA levels in intestine or liver. These results indicate that apo A-IV is regulated by MCT absorption and that fatty acid reesterification and lipoprotein assembly are not prerequisite for such regulation. Conversely, it is likely that apo B-48 participates only in the formation and/or transport of chylomicrons after LCT absorption.
Nishimura
M
M
Department of Laboratory Medicine, Gifu University School of Medicine, Japan.
Seishima
M
M
Ohashi
H
H
Noma
A
A
D000818:Animals; D053299:Apolipoprotein B-100; D053283:Apolipoprotein B-48; D001053:Apolipoproteins / Q000097:blood / Q000235:genetics / Q000378:metabolism; D001054:Apolipoproteins A / Q000378:metabolism*; D001055:Apolipoproteins B / Q000378:metabolism*; D001483:Base Sequence; D001692:Biological Transport; D002914:Chylomicrons / Q000378:metabolism; D050356:Lipid Metabolism; D008055:Lipids / Q000097:blood / Q000494:pharmacology*; D008196:Lymph / Q000378:metabolism; D008208:Lymphatic System / Q000378:metabolism*; D008297:Male; D008643:Mesentery; D015335:Molecular Probes / Q000235:genetics; D008969:Molecular Sequence Data; D011169:Portal Vein; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D053299:Apolipoprotein B-100; D053283:Apolipoprotein B-48; D001053:Apolipoproteins; D001054:Apolipoproteins A; D001055:Apolipoproteins B; D002914:Chylomicrons; D008055:Lipids; D015335:Molecular Probes; D012333:RNA, Messenger; C022205:apolipoprotein A-IV