Studies of water and electrolyte movement from oral rehydration solutions (rice‐ and glucose‐based) across a normal and secreting gut using a dual isotope tracer technique in a rat perfusion model

Abstract

Aims: To establish a model to measure bidirectional flow of water from a glucose oral rehydration solution (G‐ORS) and a newly developed rice‐based oral rehydration solution (R‐ORS) using a dual isotope tracer technique in a rat perfusion model. To measure net water, sodium and potassium absorption from the ORS. Method: In vivo steady‐state perfusion studies were carried out in normal and secreting (induced by cholera toxin) rat small intestine (n=11 in each group). To determine bidirectional flow of water from the ORS the animals were initially labelled with tritium, and deuterium was added to the perfusion solution. Sequential perfusate and blood samples were collected after attainment of steady‐state conditions and analysed for water and electrolyte content. Results: There was a significant increase in net water absorption from the R‐ORS compared to the G‐ORS in both the normal (P<0.02) and secreting intestine (P<0.05). Water efflux was significantly reduced in the R‐ORS group compared to the G‐ORS group in both the normal (P<0.01) and the secreting intestine (P<0.01). There was an increase in sodium absorption in the R‐ORS group compared to the G‐ORS. The G‐ORS produced a significantly greater blood glucose level at 75 min compared to the R‐ORS (P<0.03) in the secreting intestine. Conclusions: This study demonstrates the improved water absorption from a rice‐based ORS in both the normal and secreting intestine. Evidence that the absorption of water may be influenced by the osmolality of the ORS was also demonstrated.

Effect of osmolality on net fluid absorption in non-infected and ETEC-infected piglet small intestinal segments

“…Studying the effect of osmolality on net fluid absorption, we observed a linear increase in net fluid absorption when fluids of decreasing osmolality (sodium chloride concentrations) were used. This corresponds well to data obtained for the rat small intestine (Thillainayagam et al, 1993;Wall et al, 1997). A similar relationship was shown in ETEC-infected segments, corresponding with the correlation between osmolality and net fluid absorption for cholera toxin-induced secreting rat intestine (Cunha Ferreira et al, 1992;Pillai et al, 1994).…”

“…Although it is shown in this and several studies on rats (Farthing, 1990;Hunt et al, 1992Hunt et al, , 1994Pillai et al, 1994;Thillainayagam et al, 1993Thillainayagam et al, , 1998Wall et al, 1997), that low osmolality promotes net fluid absorption in normal and (ETEC-induced) secreting intestine, we clearly showed for the first time in piglets that hypotonic solutions do not diminish the decreased net fluid absorption due to ETEC infection. The difference between the net fluid absorption in non-infected and ETEC-infected segments is fairly independent of the osmolality of the perfusion solution.…”

Difficulty in Defecation in Infants with Gastroesophageal Reflux Treated with Smaller Volume Feeds Thickened with Rice Cereal

“…5 The net result of all these properties is significant reduction in stool volumes of patients with diarrhea who are given rice-based oral rehydration solutions. These effects of rice may be seen even in the normal intestinal epithelium 6 that is intact and noninflamed. It is therefore logical to assume that this property of rice may also be playing a role in infants with gastroesophageal reflux and normal stools when they are given rice cereal-based feeds leading to thickening in stool consistency thus making the stools difficult to pass.…”

Small Bowel Review: Part I

“…Glucose polymers (starch) and amino acids (protein) in ORS enhance sodium and, therefore, water absorption. Using a rice-based ORS, there is improved water absorption in both normal and secreting rat intestine (283). The replacement of glucose by maltodextrins, and the addition of glutamine to the standard ORS (without changing its sodium content or osmolality), result in a reduction of sodium absorption in patients with shortbowel syndrome (284).…”