Control mechanism of spontaneous in vitro contractions of the opossum sphincter of Oddi.

J. F. Helm, W. J. Dodds, J. Christensen, S. K. Sarna

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

We evaluated the control mechanism of peristaltic contractions in the opossum sphincter of Oddi (SO) by means of an in vitro preparation. At each of four sites spaced uniformly along the sphincter segment, a force transducer recorded contractions while a monopolar electrode recorded myoelectric activity. Spontaneous myoelectric and contractile activity occurred in 15 of the 20 intact SO specimens studied. Electrical recordings showed characteristic control waves and response activity. Each control wave was invariably accompanied by a phasic contraction, irrespective of whether or not response activity was superimposed on the control wave. The predominant motor activity of the SO was antegrade peristalsis. Retrograde peristalsis occurred when antegrade peristalsis failed to traverse the entire sphincter. Spontaneous SO phasic contractions were not antagonized by tetrodotoxin. Muscle rings sectioned from the SO exhibited spontaneous phasic contractions with a proximal-to-distal gradient of intrinsic contraction frequencies. We conclude that a) the frequency of SO phasic contractions is determined by control wave frequency, b) spontaneous SO peristalsis is myogenic in origin and may be modeled by a linear array of bidirectionally coupled relaxation oscillators, c) the predominance of antegrade peristalsis may be explained by a high-frequency oscillator in the proximal SO that drives the slower, more distal oscillators, d) retrograde peristalsis is initiated by an ectopic oscillator in the distal SO when antegrade contractions fail to propagate the entire length of the SO, and e) ectopic SO contractions can propagate retrograde when the more proximal oscillators are not in their absolutely refractory state.

Original languageEnglish (US)
JournalThe American journal of physiology
Volume249
Issue number5 Pt 1
StatePublished - Nov 1985
Externally publishedYes

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Sphincter of Oddi
Opossums
Peristalsis
In Vitro Techniques
Tetrodotoxin
Transducers
Electrodes
Motor Activity

ASJC Scopus subject areas

  • Medicine(all)

Cite this

Helm, J. F., Dodds, W. J., Christensen, J., & Sarna, S. K. (1985). Control mechanism of spontaneous in vitro contractions of the opossum sphincter of Oddi. The American journal of physiology, 249(5 Pt 1).

Control mechanism of spontaneous in vitro contractions of the opossum sphincter of Oddi. / Helm, J. F.; Dodds, W. J.; Christensen, J.; Sarna, S. K.

In: The American journal of physiology, Vol. 249, No. 5 Pt 1, 11.1985.

Research output: Contribution to journalArticle

Helm, J. F. ; Dodds, W. J. ; Christensen, J. ; Sarna, S. K. / Control mechanism of spontaneous in vitro contractions of the opossum sphincter of Oddi. In: The American journal of physiology. 1985 ; Vol. 249, No. 5 Pt 1.
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