Click here to close Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly. We suggest using a current version of Chrome, FireFox, or Safari.
Proc Natl Acad Sci U S A 1996 Nov 12;9323:13367-70. doi: 10.1073/pnas.93.23.13367.
Show Gene links Show Anatomy links

Cotransport of water by the Na+/glucose cotransporter.

Loo DD , Zeuthen T , Chandy G , Wright EM .

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+/CI-/gamma-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.

PubMed ID: 8917597
PMC ID: PMC24099
Article link: Proc Natl Acad Sci U S A
Grant support: [+]

References [+] :
Birnir, Voltage-clamp studies of the Na+/glucose cotransporter cloned from rabbit small intestine. 1991, Pubmed, Xenbase