Does pH of tyrode solution modify glucose and electrolyte jejunal absorption in rats?

Studies have shown that glucose is able to decrease the pH of the surface epithelium jejunal preparations when added in vitro and the existence of a high concentration of protons in the immediate area of the mucosa could be of considerable significance for absorption of electrolytes. The aim of this study is to assess whether the change in pH of Tyrode (solution used for perfusion of the jejunum) interferes with the absorption of glucose and electrolytes. Male Wistar rats weighing 200 to 220 g (n = 6) were utilized. Jejunal absorption of glucose and electrolytes was investigated in rats. A Tyrode solution containing twice glucose, sodium and potassium concentration (pH 7.0, 7.4, 8.0 and 8.5) was infused through the jejunal loops during 40 minutes. The glucose absorption was not significantly affected by Tyrode. However, there was significantly decrease in sodium absorption at pH 7.0 and 8.5 (41.13 ± 2.79 and 41.37 ± 1.71, respectively, P < 0.05) when compared with the uptake at pH 7.4 and 8.0 (61.06 ± 6.50 and 56.28 ± 7.03, respectively, P < 0.05). Moreover, potassium absorption increased at pH 8.0 (1.04 ± 0.07) when compared with the uptake at pH 7.0 (0.59 ± 0.04), 7.4 (0.78 ± 0.08) and 8.5 (0.54 ± 0.05) (P < 0.05). These data indicate that the pH of Tyrode has no influence on glucose absorption. However, the major potassium uptake occurs at pH 8.0, while the absorption of sodium is impaired at pH 7.0 and 8.5.