Effects of environmental temperature and exercise on the biochemical characteristics of hamster intestine.

The effects of increasing environmental temperature and of exercise on some biochemical characteristics of the intestinal mucosa were analyzed in hamsters to determine whether damage occurs to the intestine during exercise, because long-distance runners complain of cramp, diarrhea, or retrostaltic symptoms, especially when exercise is performed at high temperatures. Two sets of experiments were carried out on groups of five animals. First, one group stayed at rest at 20 degrees C while another group performed exercise for 30 min at the same temperature. Second, one group of animals remained at rest at 20 degrees C for 16 h, a second group was placed at 32 degrees C for the same period, and a third group was subjected to the latter treatment but in addition performed two 20-min exercises. The animals were killed immediately after the experiment. After the small bowel was removed, biopsies were taken for histological examination, and the remaining small bowel tissue was homogenized for biochemical analysis. During exercise performed at 20 degrees C or during exposure to 32 degrees C, the DNA weight (expressed as a function of the protein weight) increased; the specific activity of sucrase, leucine aminopeptidase, diamine oxidase, and maltase decreased; spermine and putrescine content generally decreased; and the weight of mucosal proteins per length of intestine did not vary significantly. When exercise was performed at 32 degrees C, we noted few modifications in the values of the intestinal parameters tested, i.e., changes in only the weight of mucosa expressed as a function of bowel length and, perhaps, the spermine or putrescine content.