EFFECTS OF GABA(A) RECEPTOR ANTAGONISM ON INSPIRATORY ACTIVITIES IN KITTENS

In anesthetized kittens (< 1 to 24 days old), the effects of GABA(A) r eceptor antagonism on phrenic, hypoglossal and cervical sympathetic di scharges were examined by i.v. bicuculline infusions during hyperoxia and hypoxia. Administration of bicuculline during hyperoxia produced m arked increases in the amplitudes of inspiratory nerve discharges. Dur ing hypoxic stimulation (10% O2), the amplitudes of inspiratory activi ties decreased towards or below those observed during hyperoxia; bicuc ulline reversed this depression and restored inspiratory discharges. O ur results indicated that GABA(A) receptors were functional shortly af ter birth, acting to mediate influences shaping inspiratory activity d uring hyperoxic breathing and during conditions of increased chemical drive.