Electrolyte Transport Across the Mouse Small Intestine 1

Abstract

Summary

The electrical and electrolyte transport properties of nonstripped mouse intestine were investigated using the Ussing chamber technique. In HCO₃-NaCl 0Ringer solution a PD of 1.47 ± 0.17 mV and I _se, of 15.8 ± 1.56 μA existed across the intestine, orientated such that the serosa was electropositive to the mucosa. Radioisotope flux measurements demonstrated net Na absorption and Cl secretion. The I _se was less than the sum of net Na and Cl fluxes (J _net ^Na + J _net ^cl), yielding a negative net residual flux (J _net ^R), indication of a simultaneous anion absorption or cation secretion. Glucose augmented J _net ^Na + J _net ^cl and increased the PD and I _sc. In the absence of bicarbonate, the J _net ^Na and J _net ^R were reduced to practically zero, suggesting that either HCO₃ ^- absorption or H⁺ secretion is responsible for the residual flux observed in HCO₃ ^- Ringer. These findings also indicate that Na absorption is HCO₃ ^- dependent.