Physical factors in the stimulation of colonic peristalsis.

The effect of colonic distension and changes in intraluminal pH and osmolality have been investigated in patients with well established colostomies. Small volumes of acidic buffer (pH4) and hypertonic saline (4%) were found to be only a very weak peristaltic stimulus. Strong hypertonic solutions (glycerine BP) induced a poorly sustained peristaltic response in the majority of cases. Distension of the inactive colon did not stimulate peristalsis. Distension of a colon previously stimulated to peristaltic activity caused fresh waves of contraction. This study appears to show that by themselves physical factors play an unimportant role in initiating peristaltic activity in the colon.