Intestinal synthesis and lymphatic secretion of apolipoprotein A-IV after cessation of duodenal fat infusion: mediation by bile.
We tested whether secretion of apolipoprotein (apo) A-IV depends upon intestinal triglyceride (TG) transport by comparing output kinetics of TG and apo A-IV during and after duodenal lipid infusion in lymph-fistula rats. Lipid infusion (triolein, 40 mumol/h, 8 h) produced increases in lymphatic TG and apo A-IV output. After 8 h, triolein infusate was replaced with glucose-saline; TG output returned to basal levels 4-5 h later. However, apo A-IV output continued at significantly elevated levels until 20 h after the start of the experiment. Bile diversion blocked this continued output of A-IV during the post-lipid period, and resulted in basal TG output that was 75% lower than in bile-intact rats. Return of bile or low-dose triolein infusion (5 mumol/h) into the intestine reversed these effects. There were no differences in hepatic synthesis or filtration of plasma A-IV into lymph between bile-intact and bile-diverted groups. Intestinal A-IV synthesis was elevated in both groups even during the post-lipid period. The results support the hypothesis that intestinal triglyceride transport drives apo A-IV secretion, and suggest the existence of a bile-dependent, post-translational mechanism for the control of lymphatic apo A-IV output.
Kalogeris
T J
TJ
Department of Surgery, Louisiana State University Medical Center, Shreveport 71130, USA. tkalog@mail.sh.lsumc.edu
Fukagawa
K
K
Tsuchiya
T
T
Qin
X
X
Tso
P
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D000818:Animals; D001054:Apolipoproteins A / Q000096:biosynthesis* / Q000378:metabolism*; D001646:Bile / Q000502:physiology*; D004041:Dietary Fats / Q000008:administration & dosage; D004386:Duodenum / Q000502:physiology; D007413:Intestinal Mucosa / Q000378:metabolism*; D007583:Jejunum / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008196:Lymph / Q000378:metabolism*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D014280:Triglycerides / Q000378:metabolism