The non-uniform character of expiratory synaptic activity in expiratory bulbospinal neurones of the cat.

摘要: Intracellular recordings were made from caudal medullary expiratory neurones in pentobarbitone-anaesthetized, vagotomized and artificially ventilated cats. The sample consisted of thirty-three bulbospinal seven which not antidromically excited either the spinal cord (C2-C3) or vagus nerve. Their rhythmic activity an alternating inspiratory hyperpolarization due to Cl(-)-dependent inhibitory post-synaptic potentials (i.p.s.p.s) (Mitchell & Herbert, 1974) depolarization. precise shape depolarizing wave varied within a given neurone depending on over-all pattern respiration. This variation extended smoothly developing depolarization, continuous throughout its course, through intermediate state depolarization proceeded two stages with definite transition between them, final early part expiration was occupied by distinct hyperpolarizing component membrane potential trajectory. Under conditions brisk phrenic nerve discharge, these variations profile related time course intensity post-inspiratory discharge However, other factors (depth anaesthesia stimulation laryngeal receptors) could influence independently discharge. In five fifteen tested, rapidly developing, decrementing i.p.s.p.s (post-inspiratory i.p.s.p.s). These present only under strong rhythm (large amplitude, fairly rapid discharge). They became weaker ultimately disappeared when level deepened slower. conditions, be restored superior Adequate presumed 'irritant' receptors elicited ten tested initially showed no possibly just weak pattern. responses current injection revealed clear differences behaviour late expiration, intensified following nerve.(ABSTRACT TRUNCATED AT 400 WORDS)