HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 544/1/253    most recent 2002.019687v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Johnson, S. M. Articles by Mitchell, G. S. Search for Related Content PubMed PubMed Citation Articles by Johnson, S. M. Articles by Mitchell, G. S.

Role of synaptic inhibition in turtle respiratory rhythm generation

Stephen M. Johnson *, Julia E. R. Wilkerson * †, Michael R. Wenninger *, Daniel R. Henderson * and Gordon S. Mitchell *

In vitro brainstem and brainstem-spinal cord preparations were used to determine the role of synaptic inhibition in respiratory rhythm generation in adult turtles. Bath application of bicuculline (a GABA_A receptor antagonist) to brainstems increased hypoglossal burst frequency and amplitude, with peak discharge shifted towards the burst onset. Strychnine (a glycine receptor antagonist) increased amplitude and frequency, and decreased burst duration, but only at relatively high concentrations (10-100 µM). Rhythmic activity persisted during combined bicuculline and strychnine application (50 µM each) with increased amplitude and frequency, decreased burst duration, and a rapid onset-decrementing burst pattern. The bicuculline-strychnine rhythm frequency decreased during µ-opioid receptor activation or decreased bath P_CO2. Synaptic inhibition blockade in the brainstem of brainstem-spinal cord preparations increased burst amplitude in spinal expiratory (pectoralis) nerves and nearly abolished spinal inspiratory activity (serratus nerves), suggesting that medullary expiratory motoneurons were mainly active. Under conditions of synaptic inhibition blockade in vitro, the turtle respiratory network was able to produce a rhythm that was sensitive to characteristic respiratory stimuli, perhaps via an expiratory (rather than inspiratory) pacemaker-driven mechanism. Thus, these data indicate that the adult turtle respiratory rhythm generator has the potential to operate in a pacemaker-driven manner.

This article has been cited by other articles:

				S. M. Johnson, L. M. Wiegel, and D. J. Majewski Are pacemaker properties required for respiratory rhythm generation in adult turtle brain stems in vitro? Am J Physiol Regulatory Integrative Comp Physiol, August 1, 2007; 293(2): R901 - R910. [Abstract] [Full Text] [PDF]

				A. Wallen-Mackenzie, H. Gezelius, M. Thoby-Brisson, A. Nygard, A. Enjin, F. Fujiyama, G. Fortin, and K. Kullander Vesicular Glutamate Transporter 2 Is Required for Central Respiratory Rhythm Generation But Not for Locomotor Central Pattern Generation. J. Neurosci., November 22, 2006; 26(47): 12294 - 12307. [Abstract] [Full Text] [PDF]

				J. Y. Sebe, J. F. van Brederode, and A. J. Berger Inhibitory Synaptic Transmission Governs Inspiratory Motoneuron Synchronization J Neurophysiol, July 1, 2006; 96(1): 391 - 403. [Abstract] [Full Text] [PDF]

				S. M. Johnson and R. J. Creighton Spinal cord injury-induced changes in breathing are not due to supraspinal plasticity in turtles (Pseudemys scripta) Am J Physiol Regulatory Integrative Comp Physiol, December 1, 2005; 289(6): R1550 - R1561. [Abstract] [Full Text] [PDF]