Uptake of ethanolamine in neuronal and glial cell cultures

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 apparentK_m of 6.7 M,V_max 41.4 pmol mg prot.^–1 min^–1 and glial cells aK_m of 119.6 M,V_max 3,917 pmol mg prot^–1 min^–1. The lower affinity of the transport and the 100 fold increase inV_max observed 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 or glutamate.