Evidence for involvement of N-methylaspartate receptors in 'wind-up' of class 2 neurones in the dorsal horn of the rat.

We have examined the effects of ketamine and kynurenate on the initial response and frequency dependent potentiation of response (wind-up) of class 2 neurones of the rat dorsal horn induced by repeated electrical stimulation of their receptive fields. Iontophoretic kynurenate reduced both the initial response and the wind-up. Iontophoretic or intravenous ketamine had no consistent effect on the initial response but consistently reduced wind-up. N-Methylaspartate receptors therefore appear to contribute to the wind-up, but not the initial response, of class 2 neurones in the rat.