|
| |
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
THE effects of tonic lung inflation on ventilation in the American bullfrog Rana catesbeiana Shaw
Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, V6T 1Z4, Canada
*Author for correspondence (e-mail: milsom{at}zoology.ubc.ca)
Accepted May 14, 2001
This study was designed to determine whether lung inflation stimulates or inhibits breathing in frogs by examining the effect of tonic lung inflation on the ‘fictive’ breathing pattern of decerebrate, unidirectionally ventilated bullfrogs. Neural discharge was monitored in the trigeminal nerve as an indication of the frequency and force of contraction of the buccal pump, and in the laryngeal branch of the vagus nerve as an indication of glottal opening, and hence fictive lung ventilation. Based on the temporal coordination of discharge in the trigeminal and vagus nerves during naturally occurring breaths it was possible to characterize the fictive breaths as inflation, deflation or balanced breaths. Increasing lung inflation increased absolute breathing frequency by reducing the duration of apnea between breaths and promoting a change in breathing pattern from no breathing to single breaths, breathing episodes and, finally, to continuous breathing. Associated with this was a decrease in the amplitude and area of the integrated trigeminal electroneurogram associated with the lung breaths, indicative of a reduction in the force of the buccal pump, and a shift in the timing of the trigeminal and vagal discharge, indicative of a shift from inflation to deflation breaths. Taken together the data suggest that lung deflation produces infrequent, large-amplitude inflation breaths or cycles, but that progressive lung inflation changes the breathing pattern to one of high-frequency attempts to deflate the lungs that are largely passive, and accompanied by contractions of the buccal pump that are no larger than those associated with normal buccal oscillations.
Key words: frog, Rana catesbeiana, ventilation, breathing pattern, lung inflation, pulmonary stretch receptor, Hering–Breuer reflex.
This article has been cited by other articles:
|
|
 |
|
  S. Fournier, M. Allard, S. Roussin, and R. Kinkead Developmental changes in central O2 chemoreflex in Rana catesbeiana: the role of noradrenergic modulation J. Exp. Biol., September 1, 2007; 210(17): 3015 - 3026. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. H. Gargaglioni, J. T. Meier, L. G. S. Branco, and W. K. Milsom Role of midbrain in the control of breathing in anuran amphibians Am J Physiol Regulatory Integrative Comp Physiol, July 1, 2007; 293(1): R447 - R457. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
O. Belzile, R. Gulemetova, and R. Kinkead Effects of medullary Raphe stimulation on fictive lung ventilation during development in Rana catesbeiana J. Exp. Biol., June 15, 2007; 210(12): 2046 - 2056. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. R. Noronha-de-Souza, K. C. Bicego, G. Michel, M. L. Glass, L. G. S. Branco, and L. H. Gargaglioni Locus coeruleus is a central chemoreceptive site in toads Am J Physiol Regulatory Integrative Comp Physiol, October 1, 2006; 291(4): R997 - R1006. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Fournier and R. Kinkead Noradrenergic modulation of respiratory motor output during tadpole development: role of {alpha}-adrenoceptors J. Exp. Biol., September 15, 2006; 209(18): 3685 - 3694. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Gheshmy, R. Vukelich, A. Noronha, and S. G. Reid Chronic hypercapnia modulates respiratory-related central pH/CO2 chemoreception in an amphibian, Bufo marinus J. Exp. Biol., March 15, 2006; 209(6): 1135 - 1146. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. Kinkead, O. Belzile, and R. Gulemetova Serotonergic modulation of respiratory motor output during tadpole development J Appl Physiol, September 1, 2002; 93(3): 936 - 946. [Abstract] [Full Text] [PDF]
|
|
