EFFECT OF MUCOSAL AMINO-ACIDS ON SCC AND NA AND CL FLUXES IN THE PORCINE SMALL-INTESTINE

Most amino acids are, like glucose, co-transported with sodium and are thereby potential additives to oral rehydration solutions for the tre atment of diarrhea. In this study the effects of mucosal amino acids o n shore-circuit current and Na and Cl fluxes in three segments of the porcine small intestine were studied. L-alanine, L-leucine, L-lysine, L-proline, L-phenylalanine and L-glutamine were added (chamber concent ration of each amino acid was 20 mmol X l(-1)) to the mucosal side of stripped proximal, mid, and distal small intestine sheets mounted in U ssing chambers in glucose containing (16 mmol X l(-1)) bathing medium; electrical parameters and unidirectional fluxes were measured. The am ino acids induced a significant elevation in mucosa to serosa flux and unaltered serosa to mucosa flux of Na in all three segments, resultin g in significant elevation in net Na absorption in proximal (2.4 +/- 0 .3 mu Eq X cm(-2) X hr(-1) to 3.5 +/- 0.3 mu Eq X cm(-2) X hr(-1), P < 0.05), mid (5.9 +/- 0.5 mu Eq X cm(-2) X hr(-1) to 8.1 +/- 0.7 mu Eq X cm(-2) X hr(-1), P < 0.05) and distal (5.9 +/- 0.6 mu Eq X cm(-2) X hr(-1) to 8.3 +/- 0.7 mu Eq X cm(-2) X hr(-1), P < 0.05) small intesti ne. The mucosa to serosa Cl flux was significantly elevated in all thr ee segments (P < 0.01) by amino acids abolishing the net Cl secretion in proximal (2.5 +/- 0.4 mu Eq X cm(-2) X hr(-1) to 0.8 +/- 0.6 mu Eq X cm(-2) X h(-1), P < 0.01) and mid (2.2 +/- 0.4 mu Eq X cm(-1) hr(-1) to 0.1 +/- 0.9 mu Eq X cm(-2) X hr(-1), P < 0.01) small intestine; Th e changes in SCC were carried by the electrogen Na absorption. In conc lusion, the amino acids, in addition eo glucose, stimulate Na absorpti on by about 1.0 mu Eq X cm(-2) X hr(-1) in the proximal part, and 2.5 mu Eq X cm(-2) X hr(-1) in the mid and distal part of the small intest ine. (C) 1997 Elsevier Science Inc.