Evidence for an intestinal Na+: Sugar transport coupling stoichiometry of 2.0 |
| |
Authors: | George A. Kimmich Joan Randles |
| |
Affiliation: | Department of Radiation Biology and Biophysics, University of Rochester Medical Center, Rochester, NY 14620 U.S.A. |
| |
Abstract: | Membrane potentials maintained by normally-energized intestinal epithelium interfere with an accurate determination of the Na+: sugar coupling stoichiometry associated with Na+-dependent transport systems. The interference is due to the fact that basal Na+ influx is itself a potential-dependent event, and sugar transport induces a membrane depolarization which therefore modifies basal Na+ entry. New information obtained under circumstances in which the membrane potential is maintained near 0 indicates that the true coupling stoichiometry is 2:1 rather than the commonly-accepted value of 1:1. A 2:1 stoichiometry means that cellular electrochemical Na+ gradients are adequate to account for recently observed 70-fold sugar gradients maintained by these cells under certain conditions. |
| |
Keywords: | Sugar transport coupling Stoichiometry (Intestinal epithelium) |
本文献已被 ScienceDirect 等数据库收录! |