THE EFFECT OF PULMONARY TONIC VAGAL INPUT ON DURATION ENDURING APNEA DURING ACUTE APNEA IN RABBIT

研究了43只麻醉、肌松和人工通气家免,切断颈迷走神经急性窒息时膈神经放电的影响。切断迷走神经后耐受窒息时间缩短(P<0.01),其中窒息潜伏期延长,兴奋期和抑制期缩短。积分膈神经活动幅度明显降低(P<0.01)。恢复期第一次中枢呼吸活动延迟。这些差别与动脉血气变化,切断喉上神经、喉返神经和腹部迷走神经无密切关系。SO_2阻断肺牵张感受器后,主要表现耐受窒息时间显著延长(P<0.01)。提示窒息时肺牵张感受器和激惹感受器的活动,经迷走神经紧张性传入,可加剧窒息时膈神经放电肥应,使耐受窒息时间延长。

THE EFFECT OF PULMONARY TONIC VAGAL INPUT ON DURATION ENDURING APNEA DURING ACUTE APNEA IN RABBIT

We studied the difference of phrenic discharge response to acute asphyxia between pre-and post-vagotomy in anesthetized, paralyzed and artificially ventilated rabbits. Bilateral Cervical vagotomy prolonged the latent period(p<0.01) but reduced the excitatory and inhibitory periods(EP,IP) and the duration enduring asphyxia during asphyxia(P<0.01). The amplitude at EP and IP and the increasing value of frequency at EP significantly decreased after vagotomy(P<0.01). The first central respiratory activity was considerably delayed (P<0.01) and its rhythm was mostly regular at recovery period after vagotomy. The differences did uot relate to the change in arterial blood gases and the cutting of superior laryngeal, recurrent laryngeal and abdominal vagal nerves. The results demonstrate that the tonic vaggal afferent activity can markedly increase the phrenie discharge response to asphyxia. The duration enduring apnea was prolonged mainly after pulmonary stretch receptor was blocked by SO_2(p<0.01). It indicated there were activities of lung stretch and irritant receptors by tonic vagat input during apnea. It heightened responses to phrenic nerve discharge and prolonged duration enduring apnea during asphyxia.