Electrical properties and active solute transport in rat small intestine
- 80 Downloads
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.
KeywordsOuabain Mucosal Membrane Phlorizin Transepithelial Potential Difference Rabbit Ileum
Unable to display preview. Download preview PDF.
- Barry, R.J.C., Dickstein, S., Matthews, J., Smyth, D.H., Wright, E.M. 1964. Electrical potentials associated with interstinal sugar transport.J. Physiol. (London) 171:316Google Scholar
- Barry, R.J.C., Eggenton, J. 1972. Membrane potentials of epithelial cells in rat small intestine.J. Physiol. (London) 277:201Google Scholar
- Barry, R.J.C., Smyth, D.H., Wright, E.M. 1965. Short-circuit current and solute transfer by rat jejunum.J. Physiol. (London) 181:410Google Scholar
- Kerkut, G.A., York, B. 1971. The Electrogenic Sodium Pump. Scientechnica, Bristol Koketsku, K. 1971. The electrogenic sodium pump.Adv. Biophys. 2:77Google Scholar
- Newey, H., Parsons, B.J., Smyth, D.H. 1959. The site of action of phlorrhizin in inhibiting intestinal absorption of glucose.J. Physiol. (London) 148:83Google Scholar
- Okada, Y., Irimajiri, A., Inouye, A. 1976b. Intracellular ion concentrations of epithelial cells in rat small intestine. Effects of external K+ and uphill transports of glucose and glycine.Jpn. J. Physiol. 24:263Google Scholar
- Wright, E.M. 1966. The origin of the glucose dependent increase in the potential difference across the tortoise small intestine,J. Physiol. (London) 185:486Google Scholar