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. Author manuscript; available in PMC: 2012 Oct 1.
Published in final edited form as: Hear Res. 2011 May 18;280(1-2):21–29. doi: 10.1016/j.heares.2011.05.003

Figure 2.

Figure 2

Schematic drawing of glucocorticoid-regulated Na+ absorption in the mouse Reissner’s membrane and rat semicircular canal duct epithelial cells. Inactive forms of glucocorticoid are activated by 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1), which then increases ENaC expression via the glucocorticoid receptor (GR) – serum glucocorticoid-regulated kinase 1 (SGK1) - Neural precursor cell-expressed developmentally downregulated 4-2 (Nedd4-2) pathway. WNK4 was also suggested to be involved in the glucocorticoid regulated-Na+ transport pathway in Reissner’s membrane. Glucocorticoid-stimulated Na+ absorption is positively regulated by phosphatidylinositol 3-kinase (PI3K) and negatively regulated by protein kinase C (PKC) in canal epithelial cells. The rate of Na+ absorption is stimulated by glucocorticoid activation of GR in mouse saccule; however, the mechanism of glucocorticoid-enhanced Na+ absorption via ENaC was not defined molecularly.