Mechanism of arachidonic acid transport across rabbit distal colonic mucosa.
The initial rate of [1-14C]arachidonic acid (AA) entry in the serosal side of rabbit distal colonic mucosa mounted in Ussing-type chambers is linear and independent of intracellular metabolism. When the maximal AA uptake was plotted as a function of medium AA concentration in ranges between 50 and 500 nM, saturation of the AA uptake with increasing concentrations was observed. The time course of the uptake of oleic acid and palmitic acid was similar to that observed with AA, and their separate addition to incubation medium strongly reduced the AA uptake. The influx of arachidonate was largely inhibited by ouabain and by incubation with mucosal sodium-free solution and amiloride, while it was increased when colonic mucosa was exposed to luminal amphotericin B. However, voltage-clamp studies showed that the AA entry rate appeared to be linearly related (r = 0.99) to transepithelial potential difference (PD) and suggested that the sodium dependence of AA translocation is an indirect effect of the changes in transepithelial PD induced by sodium transport shifts. These features provide evidence that there is a common entry pathway for AA and other long-chain free fatty acids mediated by a mechanism of facilitated diffusion driven by transmembrane PD.
Calderaro
V
V
Institute of Internal Medicine and Nephrology, University of Naples, Italy.
De Simone
B
B
Giovane
A
A
Quagliuolo
L
L
Servillo
L
L
Giordano
C
C
Balestrieri
C
C
D015117:5,8,11,14-Eicosatetraynoic Acid / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D000666:Amphotericin B / Q000494:pharmacology; D000818:Animals; D001095:Arachidonic Acids / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D002250:Carbon Radioisotopes; D003106:Colon; D004594:Electrophysiology / Q000379:methods; D004848:Epithelium / Q000502:physiology; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000187:drug effects / Q000502:physiology*; D007700:Kinetics; D008297:Male; D008564:Membrane Potentials; D019301:Oleic Acid; D009829:Oleic Acids / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000494:pharmacology; D011817:Rabbits; D011865:Radioisotope Dilution Technique; D012964:Sodium / Q000378:metabolism*
D001095:Arachidonic Acids; D002250:Carbon Radioisotopes; D009829:Oleic Acids; D010169:Palmitic Acids; D015117:5,8,11,14-Eicosatetraynoic Acid; D019301:Oleic Acid; D019308:Palmitic Acid; D010042:Ouabain; D000584:Amiloride; D000666:Amphotericin B; D012964:Sodium; D007213:Indomethacin