SEROTONIN UPTAKE BY ISOLATED ADIPOSE CAPILLARY ENDOTHELIUM

  • 1 January 1981
    • journal article
    • research article
    • Vol. 216  (1) , 125-128
Abstract
The uptake of serotinin (5-hydroxytryptamine, 5-HT) by endothelial cells was studied in freshly isolated capillary and other microvessel (< 50 .mu.m, 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 h, an apparent Km of 3 .times. 10-7 M and a Vmax of 20 pmol/mg of protein, measured at 15 min, were obtained. Uptake of 5-HT (10-6 M) was inhibited by ouabain, selected metabolic inhibitors (iodoacetate, 2-4 dinitrophenol and sodium azide), 4.degree. 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.