Transmucosal triglyceride transport rates in proximal and distal rat intestine in vivo.
Transmucosal transport rates for triolein in proximal and distal intestine were compared in unanesthetized rats. Emulsified [1-14-C] triolein together with bile and pancreatic juice from donor rats was infused for 6 hr into either the duodenum or the midpoint of the small intestine at such a rate that absorption was essentially complete in both regions of the intestine. Lymph was collected from the thoracic duct during triolein infusion and for an additional 6-hr period. The decrease in the rate of lymphatic output of labeled fat was found to follow a simple exponential function in all animals. This rate of decrease (decay rate) was used to calculate the half-times of lipid turnover through the intestinal wall and the fractional output rates. Distal intestine transported lipid 40% more slowly than proximal intestine, and the difference was associated with a greater accumulation of triglyceride in the distal intestinal wall. Chylomicron synthesis and/or release is the rate-limiting step for distal lymphatic fat transport in vivo, whereas fat uptake from the lumen is rate limiting for proximal intestine.
D000818:Animals; D001646:Bile / Q000378:metabolism; D001692:Biological Transport; D006207:Half-Life; D007413:Intestinal Mucosa / Q000378:metabolism*; D007421:Intestine, Small / Q000378:metabolism*; D007700:Kinetics; D008196:Lymph / Q000378:metabolism; D008297:Male; D008433:Mathematics; D009829:Oleic Acids / Q000378:metabolism; D009928:Organ Specificity; D010189:Pancreatic Juice / Q000378:metabolism; D051381:Rats; D013997:Time Factors; D014280:Triglycerides / Q000378:metabolism*
D009829:Oleic Acids; D014280:Triglycerides