Water and electrolyte salvage in an animal model of dehydration and malnutrition.

BACKGROUND AND AIM: Recently, a new oral rehydration solution (ORS) called Resomal has been designed specifically for children with severe malnutrition. The aim of this study was to assess the effect of malnutrition on renal and intestinal responses to dehydration, and to compare intestinal water and electrolyte absorption from Resomal and from the standard World Health Organization-Oral Rehydration Solution (WHO-ORS). METHOD: Malnutrition was achieved in a rabbit model by feeding the animals daily for 30 days with half the amount of food that a well-nourished group of control animals had consumed on the previous day. Dehydration was achieved by water deprivation for 46 hours in both control and malnourished rabbits. At 46 hours, dehydration was assessed by changes in body weight, urinary volume and osmolarity, and blood urea nitrogen concentration. At that time active colonic and jejunal mucosal electrolyte transport in Ussing chambers was also measured. Small intestinal absorption of water, sodium, and potassium was measured in vivo during intestinal perfusion of the two ORSs and in vitro by measurement of mucosal electrogenic glucose-stimulated sodium absorption across intestinal patches. RESULTS: Compared to controls (C), well-nourished but dehydrated (C+D) animals lost 12% of their body weight, with an 87% reduction in urine volume, a 110% increase in urine osmolality, and a 94% increase in blood urea nitrogen. In the colon of C+D animals, short-circuit current (Isc) and net sodium transepithelial flux (JNa+ net) were increased. Almost identical results were obtained in malnourished and dehydrated (M+D) animals. In the jejunum, net in vivo absorption of water (JWater), sodium (JNa+), and potassium (JK+) were increased during standard ORS infusion in both dehydrated groups. During Resomal infusion, water absorption was the same as seen with WHO-ORS, but sodium absorption was reduced, and potassium absorption was increased in both well-nourished and malnourished dehydrated animals. In vitro, compared to controls, the glucose-stimulated short-circuit current (DeltaIsc), JNa+ net and G were increased in both dehydrated groups. CONCLUSION: During experimental dehydration, the kidney and large intestine salvage water and electrolytes, thus reducing the consequences of dehydration. These findings indicate that jejunal water absorption from Resomal and WHO-ORS is increased during dehydration, but Resomal allows for less sodium and more potassium to be absorbed, both in well-nourished and malnourished dehydrated rabbits.

Palm versus soybean oil on intestinal recovery from malnutrition in Guinea pigs.

Recent recommendations on feeding malnourished children do not provide indication on the nature of dietary lipids. Our aim was to compare the effect of palm oil (mainly saturated and monounsaturated fatty acids) and soybean oil (mainly polyunsaturated fatty acids) on the recovery from malnutrition in guinea pigs. In a first experiment, guinea pigs received a balanced (control group) or a maize (malnourished group) diet for 7, 12, and 21 d. In a second experiment, after 12 d of malnutrition, guinea pigs received a rehabilitation diet containing palm or soybean oil. Both rehabilitation diets allowed a partial recovery from the severe weight loss induced by malnutrition. Thiobarbituric acid reactive substances content, measured in intestinal homogenates, increased in malnourished guinea pigs compared with control animals (40%, p < 0.05) and returned to near control values after rehabilitation with palm (10%) but not soybean (43%) oil diet. Intestinal short-circuit current, assessed in jejunal segments mounted in Ussing chambers, increased progressively during malnutrition (p < 0.001) and returned to near control values with both rehabilitation diets. Compared with control animals, the cell turnover (Ki-67 index assessed by immunohistochemistry detection of the Ki-67 antigen) decreased after soybean (-60%, p < 0.01) but not after palm oil. These results confirm that experimental polydeficient malnutrition induces oxidative stress and dysfunction in the intestine. They show a differential effect of palm and soybean oil on these intestinal measurements, suggesting that the composition of dietary lipids may be important in the treatment of malnutrition.