The effects of N-methyl-D-aspartate antagonism on the inspiratory activities of developing animals.

In developing kittens, antagonism of N-methyl-D-aspartate receptors by systemic injections of MK-801 produced: (a) blockage of the inspiratory off-switch, prolonging phrenic and hypoglossal discharges; (b) age-dependent changes of sympathetic inspiratory discharges, elimination of inspiratory-related discharges in animals less than or equal to 36 days old and prolongation of these discharges in older animals; (c) suppression of high-frequency oscillations in phrenic activities.