The uptake of radioactive ethanolamine has been studied in exclusively neuronal and glial cell cultures from dissociated cerebral hemispheres of chick embryos. Both cell types show saturable kinetics; neurons have an apparentKmof 6.7 μM,Vmax41.4 pmol mg prot.−1min−1and glial cells aKmof 119.6 μM,Vmax3,917 pmol mg prot−1min−1. The lower affinity of the transport and the 100 fold increase inVmaxobserved in glial cells correlated with a more important accumulation of free ethanolamine found in glial cells and with a higher degree of phosphorylation of ethanolamine. The uptake appeared to be temperature and Na+ions dependent but was not affected by CN−or ouabain. Monomethyl-, dimethylethanolamine and choline were effective in inhibiting the uptake. Little or no effect was observed with serine, methionine, carnitine, alanine o
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