Serotonin uptake by isolated adipose capillary endothelium.
The uptake of serotinin (5-hydroxytryptamine, 5-HT) by endothelial cells was studied in freshly isolated capillary and other microvessel (< 50 micrometers, inner diameter) endothelium obtained from rat epididymal fat pads. Endothelial cells incubated with [3H]-5-HT removed 60 pmol of [3H]-5-HT per mg of protein at 1 hr, an apparent Km of 3 X 10(-7) M and a Vmax of 20 pmol/mg of protein, measured at 15 min, were obtained. Uptake of 5-HT (10(-6) of M) was inhibited by ouabain, selected metabolic inhibitors (iodoacetate, 2--4 dinitrophenol and sodium azide), 4 degrees C, tryptamine (10(-5) M and the 5-HT antagonists, fluoxetine and imipramine (10(-5) M and 10(-4) M, respectively). At concentrations of 5-HT greater than Km value, uptake appears to be principally by nonfacilitative diffusion rather than by carrier-mediated transport.
D000273:Adipose Tissue / Q000098:blood supply; D000818:Animals; D000963:Antimetabolites / Q000494:pharmacology; D002196:Capillaries / Q000378:metabolism*; D004727:Endothelium / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D010042:Ouabain / Q000494:pharmacology; D051381:Rats; D012701:Serotonin / Q000031:analogs & derivatives / Q000378:metabolism*
D000963:Antimetabolites; D012701:Serotonin; D010042:Ouabain