Pathophysiological mechanisms of diarrhoeal diseases: diverse aetiologies and common mechanisms

A detailed review of the pathophysiology of diarrhoeal diseases is presented. Recent developments in the understanding of the mechanisms by which water absorption occurs via electrolyte transport are detailed. The secretion of Cl across the apical membrane in vivo is accompanied by a flow of Na as a counter ion, probably via the paracellular pathway. Normal regulation of active intestinal ion transport depends on cyclic AMP and cyclic GMP as well as intracellular calcium. In diarrhoeal diseases, some portion of the gut is usually found to be in a secretory rather than absorptive condition. This may be due to changes in active ion transport (decrease in Na absorption or increase in Cl secretion), alterations in intestinal motility and/or luminal osmolarity or to an increase in tissue hydrostatic pressure.