Summary
Addition ofd-glucose to the mucosal fluid resulted in a significant depolarization of the mucosal membrane potential (V m) in rat duodenum, jejunum, and ileum accompanied by an increase in the transepithelial potential difference (PD t). On the other hand,l-glucose did not inducePD t andV m changes. Glycine applied from the mucosal side also inducedV m-depolarization andPD t-increment in the ileum. Phlorizin added to the mucosal fluid or ouabain added to the serosal fluid inhibited the sugar-dependent changes inPD t andV m.
According to the analysis with an equivalent circuit model for the epithelium, it was concluded that an actively transported solute induced not only a depolarization of the mucosal (brush border) membrane but also a hyperpolarization of the serosal (baso-lateral) membrane of an epithelial cell, so that the origin of solute-inducedPD t changes should be attributed to changes in emf's at both membranes. The hyperpolarization of the serosal membrane in the presence of an actively transported solute was attributed to a mechanism of serosal electrogenic sodium pump stimulated by the increase in the extrusion rate of Na+ co-transported into the cell with sugar or amino acid.
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Okada, Y., Tsuchiya, W., Irimajiri, A. et al. Electrical properties and active solute transport in rat small intestine. J. Membrain Biol. 31, 205–219 (1977). https://doi.org/10.1007/BF01869405
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DOI: https://doi.org/10.1007/BF01869405