AJP - Gastrointestinal and Liver Physiology, Vol 271, Issue 2 322-G329, Copyright © 1996 by American Physiological Society
Effects of lipid administration on lymphatic apolipoprotein A-IV and B output and synthesis
M. Nishimura, M. Seishima, H. Ohashi and A. Noma
Department of Laboratory Medicine, Gifu University School of Medicine, Japan.
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.
