A method for simultaneous recording and assessment of gut contractions and relaxations in vivo.

The normal gut exhibits both contractions and relaxation from a resting tonus. Pathological and pharmacological information may be gleaned from separate measurement of these activities. Methods for recording and analyzing gut contractions have been presented before. We present an extension to the methods, utilising simple foil strain gauges tested here in male Sprague-Dawley rats. Coupled with a computer-based data acquisition and analysis system, we could assess the relaxation and contraction waves recorded simultaneously and from different gut regions in vivo. In contrast with the antrum, where spontaneous motor activity consisted of low frequency relaxations and random contractions, spontaneous duodenal motility was patterned into periodic groups of intense activity interposed by periods of low amplitude, low frequency contractions and relaxations. This grouped activity was propagatory, reminiscent of migrating myoelectrical complexes. When challenged with the ulcerogen cysteamine-HCl (56 mg/100 g s.c.), only duodenal motor activity was affected. Moreover, this treatment had differential effects in the duodenum. Patterned motility was no longer distinguishable, and contraction frequency and amplitude were increased while relaxation amplitude was decreased. This method affords a particularly sensitive and more precise assessment of both contractile and relaxant motor activity in vivo, before and after drug treatment.