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A gastrointestinal role for the amphibian ‘diaphragm’ of Xenopus laevis
Author(s) -
Pickering Mark,
Campion Deirdre,
Jones James F. X.
Publication year - 2004
Publication title -
journal of zoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 96
eISSN - 1469-7998
pISSN - 0952-8369
DOI - 10.1017/s0952836904005497
Subject(s) - xenopus , diaphragm (acoustics) , amphibian , biology , anatomy , stimulation , diaphragmatic breathing , esophagus , toad , medicine , endocrinology , pathology , biochemistry , ecology , physics , alternative medicine , gene , acoustics , loudspeaker
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 · mmHg 2 (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·mmHg 2 ). 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.