EFFECTS OF K-DEPOLARIZATION, ARACHIDONIC-ACID, ETHANOL, AND AGING ON THE HIGH-AFFINITY CHOLINE TRANSPORT IN RAT HIPPOCAMPUS()

The Na+-dependent high-affinity choline uptake (HACU) transport and th e [H-3]hemicholinium-3 ([H-3]HC-3) specific binding were measured on h ippocampal synaptosomes of young (3-6 months) and old (22 months) Wist ar rats. In vitro effects of 100-300 mu M arachidonic acid (PLA) and o f 5% ethanol were tested under basal as well as stimulated (55 mM KCl) conditions. The influence of AA (an irreversible decrease of HACU and a reversible increase of [H-3]HC-3 binding) was more marked under sti mulated rather than basal conditions in brain tissue of young rats. Th e increased K+-depolarization effect on HACU and the decreased influen ce of AA on [H-3]HC-3 binding were estimated in brain tissue of old co mpared to young rats. Results suggest the involvement of different poo ls of the high-affinity choline carrier and marked changes due to agin g in the regulation of the HACU transport.