Dihydrokainic acid affects extracellular taurine and phosphoethanolamine levels in the hippocampus

The specificity of the inhibitory effect of dihydrokainic acid on the high-affinity glutamate uptake was tested in an in vivo system. The rabbit hippocampus was perfused with Krebs--Ringer bicarbonate medium to which dihydrokainic acid was added (final concentrations 1 and 5 mM) with or without depolarizing potassium concentrations. Dihydrokainate elevated the levels of glutamate, taurine and phosphoethanolamine. This response was partly similar to that observed after high potassium administration. The selectivity of dihydrokainic acid is thus not restricted to glutamate, and its value as a tool in the study of glutamatergic transmission is discussed.