PHYSIOLOGICAL SIGNIFICANCE OF THE CONTRACTIONS OF THE RABBIT PROXIMAL COLON

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Abstract
In humans and in carnivores, the motor activity of the colon was separated into various types based on records of the intraluminal pressure. However, little is actually known about the physiological significance of the various pressure waves. The basic pattern of colonic motility in a herbivorous species. Motility of the proximal colon was studied by strain gauge transducer records combined either with fluoroscopy or by direct visual observation in conscious and anesthetized rabbits. In the proximal colon 3 types of contractions were found: high frequency repetitive contractions, low frequency rises of the base line and monophasic progressive waves. The frequency of the repetitive contractions was 13.8 contractions/min at the oral site and 16.3 contractions/min at the aboral site of the proximal colon. The mean duration of the repetitive contractions was 3.2 .+-. 1 s. They coincided with orally migrating (1-2 mm/s) shallow annular constrictions which represented haustral activity. The low frequency rises of the base line (mean duration 131 .+-. 47 s) were associated with aborally migrating (7 mm/min) deep annular constrictions representing segmental activity. The monophasic progressive waves represented peristaltic contractions. The mean durations of the monophasic waves were 5.5 .+-. 1.2 s (period of hard feces formation), and 9.7 .+-. 2.8 s (period of soft feces formation), the average rates of progression were 3.2 .+-. 1.2 cm/s (period of hard feces production) and 1.3 .+-. 0.6 cm/s (period of soft feces production). Colonic motility of rabbits consisted of a complex motor pattern. The present classification was similar but not identical with that described in carnivores and man. Further comparative studies on other mammals are necessary to decide whether the motor activity of the colon is comparable between various species.

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