THE LATENT PERIOD OF INTESTINAL MUSCLE

Abstract

A gradation in latent period of muscular contraction with short intervals in the duodenum and longer ones in the ileum has been demonstrated in the small intestine of several species. There was little if any change in the latent period when the bowel was excised and placed in warm aerated balanced saline solution. In the small bowel of the rabbit faradic tetanic stimulation, after an interval of approximately 0.2 sec., usually produced a contraction in which the lever rose slowly for 1 or 2 sec. and then rose rapidly. With galvanic stimuli the lever rose rapidly from the start and the resultant curve was different from that obtained with faradic stimuli. The latent period was a little shorter than with the faradic current. The presence of 2 components in the curve of contraction obtained with faradic stimuli but not with galvanic seems best explained by the assumption that the 1st rise is due to a direct effect on the muscle and the 2nd to an effect transmitted by the nervous system. The gradient of latent period may perhaps help to determine the direction of normal diastalsis; it is suggestive that it was found flattened or reversed in several distempered dogs and a few pregnant cats.