Jejunal water and electrolyte secretion induced by L-arginine in man

In this study a perfusion technique has been used to investigate jejunal secretion in response to the dibasic amino acid L-arginine. L-arginine at 5, 15, and 40 mmol/l in isotonic saline solutions induced net intestinal secretion of water and Na+. The structurally similar dibasic amino acid L-lysine caused net absorption at 5 and 15 mmol/l, and only modest net secretion of water and Na+ at 40 mmol/l, although absorption rates of the two amino acids were similar. D-arginine (15 mmol/l) was without effect on net water and Na+ absorption. L-arginine 15 mmol/l inhibited glucose-stimulated water and Na+ absorption when perfused in the same intestinal segment, but was without effect when perfused in separate jejunal or ileal segments. Parenteral chlorpromazine inhibited L-arginine induced jejunal water and Na+ secretion. Jejunal secretion induced by L-arginine thus appears not to be due to passive osmotic water flow, nor to release of circulating secretagogues. Stimulation of a mucosal secretory process is most likely to be the mechanism.