The role of human perfusion techniques in the assessment of oral rehydration solutions.

Early human intestinal perfusion studies provided valuable information on gut transport procession in vivo. Subsequently, similar models have proved a useful means of assessing the efficacy of glucose-electrolyte oral rehydration solutions. In contrast to clinical trials they enable quantification of water and solute movement across the small intestine and, unlike animal studies, results are directly applicable to man. However, limitations exist, including the fact that a short, usually normal, segment of intestine is studied. Recent studies confirm the relationship between oral rehydration solution sodium concentration and sodium movement; the stimulatory effect of glucose on sodium and water movement; and the detrimental effect of high glucose content. Glycine, bicarbonate, citrate and acetate provide little additional benefit for water absorption when added to solutions containing glucose. Preliminary comparative studies of results obtained in the rat and in man show parallels between these models suggesting they may be complimentary methods of assessing new oral rehydration solutions.