The effect of L-arginine on absorption of a glucose-electrolyte solution in humans

The purpose of this study was to determine the effect of a low concentration of L-arginine (Arg) on water absorption from an isotonic glucose-electrolyte solution (GES). Six healthy human subjects (mean ± SD age = 23 ± 2 yr) participated. The GES tested were 222 mM glucose (G), 222 mM glucose + 1.5 mM Arg (G + 1.5 Arg), and 222 mM glucose + 3 mM Arg (G + 3 Arg). To control for the effect of glucose on water absorption, a 222 mM fructose + 1.5 mM Arg (F + 1.5 Arg) solution was also tested. Solutions also contained 20 mEq sodium and 3 mEq potassium (osmolalites = ~270 mOsm/kgH₂O). Water absorption was not different among G, G + 1.5 Arg, and G + 3 Arg. The respective medians (ranges) for those solutions were 5.5 (4.1 to 9.7), 6.6 (2.3 to 7.9), and 5.8 (3.9 to 13.6) ml/h/cm. Each of the glucose-containing solutions promoted faster (P=0.05) absorption than F + 1.5 Arg, which had an absorption rate of 0.8 (-1.7 to 3.0) ml/h/cm. These results indicate water absorption from an isotonic GES in healthy humans is not affected by addition of low concentrations of Arg (1.5 to 3 mM).