RESUMEN
To investigate the effect of substrates during oral rehydration therapy, we studied intestinal cation cotransport (ICC) with glutamine (Gln) alanine (Ala) and glucose (Glu). The specific aims were to determine the biological effects of these three different cotransport systems on intestinal function. Isolated rabbit ileal mucosa preparations mounted in Ussing chambers were studied. ICC was determined by measuring short-circuit current (Isc) and potential difference (PD) while monitoring toissue resistance (TR). The data are reported as the mean ñ SEM of 4-6 experiments for each amino acid concentration. Increasing concentrations of Gln (10-5 to 10-2 M), Ala (10-5 to 10-1 M) and Glu (10-5 to 10-2 M) caused a significant (P<0.05) increase in ICC. Glin (30 mM) and Ala (0.1 M) had a maximal effects (Em (Glin)=100% anmd Em (Ala)=66%, P<0.05) which was higher than that obtained with 30 mM Glu (Em (Glu)=35%). When sodium was replaced with choline on the mucosal side. Ringer solution completeley abolished the response with Gln, Ala and Glu. The presence of all three substrates (10-2 M gln, 10-1 M Ala and 10-2 M Glu) in Ringer solution on the mucosal side caused a significant increase in ICC ( increase of short circuit current = III ñ 43 uA, P<0.05). These results demonstrate that Glin, Ala and Glu each increased sodium-dependent cation cotransport, and that sodium-dependent intestinal cation cotransport was higher with Gln than with Ala or Glu
Asunto(s)
Conejos , Alanina , Aminoácidos , Fluidoterapia , Glucosa , Glutamina , Íleon , Intestinos/fisiología , Membrana Mucosa , Sodio , CationesRESUMEN
Malnutrition and dehydration are the immediated consequences of diarrheal diseases. To investigate the biological significance ofglutamine, alanine and glucose in the intestinal mucosa, we have used Ussing chambers to determine electrolyte transport by measuring short-circuit current (Isc), potential difference (PD) and tissue resistance (TR) in rabbit intestinal mucosa. Increasing doses (10-5 M to 10-1 M)of glutamine,alanine and glucose cause a significant increase in intestinal cation cotransport. Although glucose had a slightly earlier effect, 30mM glutamine and 0.1 M alanine had a maximal effect which was more than two times that caused by 30 nM glucose. The pD2 values for glucose, glutamine and alanine were 3.0, 2.5, and 2.0, respectively. The dose-response curves of these substrates suggest that the intestinal cotransport kinetics for glutamine is differentfrom that of glucose and alanine. Our results demonstrated that all three substrates cause a significant increase in Isc or PD, suggesting an increase in the intestinal mucosa cation cotransport. Glutamine has a larger effect on cation cotransport than alanine and glucose. These combinations should be studied further for the development of an oral rehydrating solution for diarrhea treatment which could prevent the resulting malnutrition, especially in those cases of prolonged diarrheal diseases