ABSTRACT
Segments of rabbit colon were sectioned and stained with haematoxylin and eosin to determine the extent of the colitis, the appearance of the lamina propria, submucosa, muscularis mucosae and mucosa with respect to ulceration, abscesses and neutrophil aggregation. Longitudinal muscle, circular muscle and the muscularis mucosae from both control and colitis tissue responded to acetylcholine with concentration-related contractions. In inflammatory bowel disease there are significant histologic changes in the appearance of each of the three muscle layers which comprise the affected area of the intestine. A length-tension relationship was established for each control and colitis muscle type under isometric recording conditions. The responses of each of the three muscle layers of both the normal and colitic distal colon to histamine are shown in figure 2D. The intracellular basis of the phenomenon of desensitization has been studied in a number of physiological systems including vascular smooth muscle, cardiac muscle, skeletal muscle, tracheal smooth muscle32 and neuronal tissue.
