Reappraisal of the inspiratory effect of Bötzinger complex on phrenic nerve discharge.
Experiments were done on 12 urethane-chloralose anaesthetized, vagotomized, paralysed and ventilated cats. The effects of electrical microstimulation at the augmenting expiratory neurons (Aug-e) of Bötzinger complex (Bot.c) were investigated. It was found that long train stimulation (100 Hz, 3-50 microA, 4-6 s) caused intensity-dependent inhibition of phrenic inspiratory discharge. The threshold for complete inhibition was 10 +/- 2 microA (mean +/- S.E.). The expiratory duration showed shortening at low intensity (< 7 microA) and prolongation at higher intensity. Short train stimulation (10 microA, 50 ms) delivered in inspiratory phase produced a two-part transient inhibition of phrenic discharge. The latencies of the first- and second-part inhibition were 4.7 +/- 0.16 ms and 95 +/- 3 ms, respectively. Complete termination of inspiration could be produced by a short train delivered at late inspiration. The results suggest the importance of the Aug-e neurons of Bot.c in determining inspiratory amplitude and respiratory phase duration.
Department of Physiology, Shandong Medical University, Jinan, People's Republic of China.
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Gang
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Lei
D018686:Anesthetics, Intravenous / Q000494:pharmacology; D000818:Animals; D002415:Cats; D002698:Chloralose / Q000494:pharmacology; D004558:Electric Stimulation; D004594:Electrophysiology; D005260:Female; D006653:Histology; D008297:Male; D008839:Microelectrodes; D010791:Phrenic Nerve / Q000378:metabolism*; D012119:Respiration / Q000502:physiology*; D014520:Urethane / Q000494:pharmacology
D018686:Anesthetics, Intravenous; D002698:Chloralose; D014520:Urethane