Effect of aquaporin 5 on paracellular water secretion in rat submandibular gland acini

概要

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We examined the influence of aquaporin 5 (AQP 5) on the paracellular transport of submandibular gland acini in Wistar rats focusing on elucidation of both AQP 5 and the junctional protein localization. In the control gland, although immunocytochemistry revealed expression of AQP 5 along the luminal membrane, it was not detected on the lateral membrane in the acinar cells. However, both E-cadherin and β-catenin were detected on the lateral membrane. In the gland stimulated by pilocarpine, localization of AQP 5 was similar to that in the control gland. In addition, there was positive staining of the lateral membrane. However, β-catenin disappeared on the luminal membrane. This is because water-rich fluid is secreted in the lumen of the acinar cells where AQP 5 is abundant, and because the tight junction is permeable. It is reasonable to speculate that both intracellular and paracellular transport play important roles concomitantly in water secretion. These results indicate that AQP 5 facilitates fluid secretion via the paracellular pathway in submandibular gland acini, and that the luminal membrane of gland acinar cells is the rate-limiting barrier to water movement.
大阪歯科学会の論文