Linolenic acid transport in hamster intestinal cells is carrier-mediated.
The intestinal uptake of [1-14C]linolenic acid [18:3(n-3)], an essential fatty acid, was investigated in isolated hamster intestinal cells using a rapid filtration method and 20 mmol/L taurocholate as solubilizing agent. Under these conditions, the initial rate of alpha-linolenic acid uptake was not a linear function of external monomer concentrations in the range of 2 to 2250 nmol/L, but rather the transport system was characterized by saturation kinetics with Vmax = 11.37 nmol.mg protein-1.min-1 and Km = 382 nmol/L. Temperature and metabolic poisons (2,4-dinitrophenol, antimycin A) drastically decreased the initial rate of uptake, as did replacement of Na+. The presence of excess unlabeled alpha-linolenic acid in the incubation medium significantly inhibited the uptake of [1-14C]linolenic acid, whereas L-alanine and D-glucose had no effect. Other long-chain fatty acids (saturated or unsaturated), as well as cholesterol, inhibited the uptake of [1-14C]linolenic acid. We concluded that an active, carrier-mediated mechanism was involved in the intestinal transport of alpha-linolenic acid. Inhibition data are compatible with the hypothesis that intestinal uptake of alpha-linolenic acid is mediated by a carrier common to long-chain fatty acids.
Goré
J
J
Laboratoire de Physiologie et Biophysique Cellulaires, Faculté des Sciences Pharmaceutiques, Tours, France.
Hoinard
C
C
D000818:Animals; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D002250:Carbon Radioisotopes; D002478:Cells, Cultured; D006224:Cricetinae; D004337:Drug Carriers / Q000494:pharmacology*; D005227:Fatty Acids / Q000494:pharmacology; D007408:Intestinal Absorption / Q000187:drug effects / Q000502:physiology*; D007421:Intestine, Small / Q000378:metabolism; D008042:Linolenic Acids / Q000032:analysis / Q000037:antagonists & inhibitors / Q000493:pharmacokinetics*; D008297:Male; D012964:Sodium / Q000494:pharmacology; D013656:Taurocholic Acid / Q000494:pharmacology; D013696:Temperature
D002250:Carbon Radioisotopes; D004337:Drug Carriers; D005227:Fatty Acids; D008042:Linolenic Acids; D013656:Taurocholic Acid; D012964:Sodium