The primary afferent depolarizing action of kainate in the rat.
Dorsal roots (L3-L7) isolated from immature (1-9 day old) rats were depolarized selectively by kainate (1-100 microM). L-Glutamate (25-100 microM), but not L-aspartate, mimicked the action of kainate. N-methylaspartate had no activity on these preparations and quisqualate was thirty times less active than kainate. Depolarizations evoked by L-glutamate (100-1000 microM) faded rapidly in the presence of L-glutamate. Depolarizations evoked by kainate were depressed during the fade induced by L-glutamate. Certain electrically evoked C-fibre volleys in dorsal roots or leg nerves of rats at any age were selectively depressed or abolished in the presence of kainate. The effect of kainate was more selective than that of gamma-aminobutyric acid or capsaicin. Prolonged treatment of dorsal roots with kainate did not appear to be deleterious to C-fibres. It is suggested that certain primary afferent C-fibres possess kainate receptors which may be activated physiologically by L-glutamate released at their central terminations.
D000200:Action Potentials / Q000187:drug effects; D000344:Afferent Pathways / Q000187:drug effects*; D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D002211:Capsaicin / Q000494:pharmacology; D005071:Evoked Potentials / Q000187:drug effects; D005971:Glutamates / Q000494:pharmacology; D066298:In Vitro Techniques; D007608:Kainic Acid / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D016202:N-Methylaspartate; D009412:Nerve Fibers / Q000187:drug effects*; D010069:Oxadiazoles / Q000494:pharmacology; D016318:Quisqualic Acid; D051381:Rats; D013126:Spinal Nerve Roots / Q000187:drug effects; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D005971:Glutamates; D010069:Oxadiazoles; D001224:Aspartic Acid; D005680:gamma-Aminobutyric Acid; D016202:N-Methylaspartate; D016318:Quisqualic Acid; D002211:Capsaicin; D007608:Kainic Acid