[Role of Ca2+ and aquaporin-2 in regulation of basolateral water permeability of collecting ducts in the rat kidney].

The role of AQP2,3 and intracellular calcium in vasopressin-induced increase in the water permeability of the basolateral cell membrane in microdissected rat kidney OMCD was studied. It was shown that increase in the water permeability of the basolateral membranes correlated with increase in the content of AQP2 and AQP3 in the membrane fraction isolated from outer kidney medulla. Preliminary loading of cells with BAPTA-AM which binds intracellular Ca2+ abolished the increase in the water permeability and prevented the rise of the AQP2 content in response to dDAVP. BAPTA was ineffective to block the enhancement of AQP2 content in membrane fraction in presence of dDAVP. These results suggest that the increase in intracellular calcium activity and the enhanced content of AQP2 in plasma membrane are important for the antidiuretic effect of dDAVP.