[Current concepts in the pathophysiology of the diarrhea (author's transl)].

Diarrhea can be defined as increased frequency of bowel movements (greater than 3 per day) plus decreased consistency of stools (volume greater than 200 ml per defecation). Two pathogenetic mechanisms have been intensively investigated and partially elucidated within the last years: 1. Secretion of electrolytes and water by way of induction of an augmented synthesis of cAMP in the mucosa cell. Cholera enterotoxin and other bacterial toxins as well as VIP (vasoactive intestinal peptide) cause diarrhea by this mechanism. 2. Certain substances such as dihydroxylated bile acids, diphenolic laxatives and probably fatty acids cause leakage of the tight junctions between mucosal cells and cause leakage of electrolytes and water back into the intestinal lumen.