Document Type

Article

Publication Date

6-2001

Publication Source

The Journal of Biological Chemistry

Abstract

Aquaporins (AQPs) are channel proteins that regulate the movement of water through the plasma membrane of secretory and absorptive cells in response to osmotic gradients. In the salivary gland, AQP5 is the major aquaporin expressed on the apical membrane of acinar cells. Previous studies have shown that the volume of saliva secreted by AQP5-deficient mice is decreased, indicating a role for AQP5 in saliva secretion; however, the mechanism by which AQP5 regulates water transport in salivary acinar cells remains to be determined. Here we show that the decreased salivary flow rate and increased tonicity of the saliva secreted byAqp5 /− mice in response to pilocarpine stimulation are not caused by changes in whole body fluid homeostasis, indicated by similar blood gas and electrolyte concentrations in urine and blood in wild-type and AQP5-deficient mice. In contrast, the water permeability in parotid and sublingual acinar cells isolated from Aqp5 /− mice is decreased significantly. Water permeability decreased by 65% in parotid and 77% in sublingual acinar cells fromAqp5 /−mice in response to hypertonicity-induced cell shrinkage and hypotonicity-induced cell swelling. These data show that AQP5 is the major pathway for regulating the water permeability in acinar cells, a critical property of the plasma membrane which determines the flow rate and ionic composition of secreted saliva.

Inclusive pages

23413-23420

ISBN/ISSN

0021-9258

Document Version

Published Version

Comments

This document is provided for download in compliance with the publisher's policy on self-archiving. Permission documentation is on file.

Publisher

The American Society for Biochemistry and Molecular Biology

Volume

276

Issue

26

Peer Reviewed

yes


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