Glutamine-induced membrane currents in cultured chick spinal cord neurons

The effects of L-glutamine (GLN) on cultured spinal cord neurons from the chick were studied in the whole cell mode of the patch clamp technique. GLN induced membrane currents rectified at positive membrane potentials (m.p.) and reversed polarity close to zero m.p. The dose-response curve was nearly linear at a semilogarithmic scale for concentrations of 10(-5) M-10(-2) M. Summation of the responses evoked by GLN (10(-3) M) and glycine (10(-3) M) was observed when these two amino acids were applied together, while no significant increase of the responses was present when GLN was applied together with L-glutamate (10(-3) M) or kainate (10(-3) M). It is suggested that GLN binds to the glutamate receptors and activates the same type of ionic channels as glutamate and kainate.