Temporal patterns of trigeminal respiratory activity in rat brainstem-spinal cord in vitro

RESPIRATORY activity in trigeminal (V) motoneurons was studied in rhythmica lly active en bloc brainstem-spinal cord preparations isolated from neonata l rats (P0-P3). In the majority of preparations (83%), the temporal pattern of V activity consisted of spontaneous inspiratory phasic discharge with o nset delayed or coincident with onset of phrenic motoneuron discharge. Bloc kade of alpha-2 noradrenergic receptor activation shifted onset of V respir atory discharges earlier than phrenic discharges, while elevation of extrac ellular potassium concentration or blockade of GABAergic and glycinergic in hibitory synaptic transmission had little effect on temporary pattern of V respiratory discharges. We conclude V motoneurons in the in vitro preparati on generate respiratory activity during inspiratory phase, and their tempor al patterns are modulated by inhibitory noradrenergic synaptic transmission . (C) 1999 Lippincott Williams & Wilkins.