Cotransport of water by the Na ⁺ /glucose cotransporter

• Donald D. F. Loo

  Department of Physiology, University of California School of Medicine, Los Angeles, CA 90095-1751; Department of Medical Physiology, The Panum Institute, University of Copenhagen, DK-2200 Copenhagen, N-Denmark; and Department of Physiology and Biophysics, University of California School of Medicine, Irvine, CA 92717

• Thomas Zeuthen

  Department of Physiology, University of California School of Medicine, Los Angeles, CA 90095-1751; Department of Medical Physiology, The Panum Institute, University of Copenhagen, DK-2200 Copenhagen, N-Denmark; and Department of Physiology and Biophysics, University of California School of Medicine, Irvine, CA 92717

• Grischa Chandy

  Department of Physiology, University of California School of Medicine, Los Angeles, CA 90095-1751; Department of Medical Physiology, The Panum Institute, University of Copenhagen, DK-2200 Copenhagen, N-Denmark; and Department of Physiology and Biophysics, University of California School of Medicine, Irvine, CA 92717

• Ernest M. Wright

  Department of Physiology, University of California School of Medicine, Los Angeles, CA 90095-1751; Department of Medical Physiology, The Panum Institute, University of Copenhagen, DK-2200 Copenhagen, N-Denmark; and Department of Physiology and Biophysics, University of California School of Medicine, Irvine, CA 92717

抄録

Water is transported across epithelial membranes in the absence of any hydrostatic or osmotic gradients. A prime example is the small intestine, where 10 liters of water are absorbed each day. Although water absorption is secondary to active solute transport, the coupling mechanism between solute and water flow is not understood. We have tested the hypothesis that water transport is directly linked to solute transport by cotransport proteins such as the brush border Na + /glucose cotransporter. The Na + /glucose cotransporter was expressed in Xenopus oocytes, and the changes in cell volume were measured under sugar-transporting and nontransporting conditions. We demonstrate that 260 water molecules are directly coupled to each sugar molecule transported and estimate that in the human intestine this accounts for 5 liters of water absorption per day. Other animal and plant cotransporters such as the Na + /Cl − /γ-aminobutyric acid, Na + /iodide and H + /amino acid transporters are also able to transport water and this suggests that cotransporters play an important role in water homeostasis.

収録刊行物

• Proceedings of the National Academy of Sciences

  Proceedings of the National Academy of Sciences 93 (23), 13367-13370, 1996-11-12

  Proceedings of the National Academy of Sciences

キーワード

• Multidisciplinary

詳細情報

• CRID: 1363951795016674176
• NII論文ID: 30016223270
• DOI: 10.1073/pnas.93.23.13367
• ISSN: 10916490
• ISSN: 00278424
• Web Site: https://pnas.org/doi/pdf/10.1073/pnas.93.23.13367
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