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A gastrointestinal role for the amphibian ‘diaphragm’ of Xenopus laevis

Published online by Cambridge University Press:  12 August 2004

Mark Pickering ,
Deirdre Campion  and
James F. X. Jones
Mark Pickering
Affiliation:
Conway Institute of Biomolecular and Biomedical Research, Department of Human Anatomy and Physiology, University College Dublin, Earlsfort Terrace, Dublin 2, Ireland
Deirdre Campion
Affiliation:
Department of Veterinary Physiology and Biochemistry, University College Dublin, Belfield, Dublin 2, Ireland
James F. X. Jones
Affiliation:
Conway Institute of Biomolecular and Biomedical Research, Department of Human Anatomy and Physiology, University College Dublin, Earlsfort Terrace, Dublin 2, Ireland
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Abstract

The ‘diaphragm’ of Xenopus laevis has close anatomical relations to the lower end of the oesophagus. In mammals, the crural diaphragm acts as a pinch valve at the gastro-oesophageal junction and is an important component of the gastro-oesophageal reflux barrier. The present study analysed the effect of amphibian ‘diaphragm’ contraction on oesophageal pressure using a superfused in situ oesophago-diaphragmatic preparation of large female Xenopus. Three-dimensional reconstruction of the oesophageal pressure profile was performed using four-port oesophageal infusion manometry. Bilateral electrical stimulation of the nerves supplying the ‘diaphragm’ of Xenopus increased the pressure volume vector of 5 mm of oesophagus (centred around the insertions of the diaphragm) from 20.4±16 to 553.6±232 mm.mmHg2 (mean±sd). This was a statistically significant increase and statistically significantly higher than that evoked by electrical stimulation of both vagi (28.1±30.7 mm.mmHg2). The amphibian ‘diaphragm’ seems to be functionally similar to the mammalian crural diaphragm. By analogy, we suggest that the original role of the diaphragm was not respiratory but gastrointestinal.

Keywords

diaphragmoesophagusamphibianXenopus laevis
Type
Research Article
Information
Journal of Zoology , Volume 264 , Issue 1 , January 2004 , pp. 45 - 51
Copyright
© 2004 The Zoological Society of London

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