Role of AQP2 in activation of calcium entry by hypotonicity: implications in cell volume regulation

摘要

the kidney collecting duct plays an important role in the process of urine concentration through a mechanism regulated by arginine vasopressin. This hormone induces an increase in osmotic water permeability (Pf) by triggering translocation and fusion of intracellular vesicles containing aquaporin 2 (AQP2) to the apical membrane of principal cells (32, 33, 48). In this condition, two-thirds of the hyposmotic luminal fluid entering the cortical collecting duct (CCD) is reabsorbed. Therefore, CCD cells are faced with both, changes in apical osmolarity and important volume flows which could result in cell volume increases. For this reason, potent volume regulatory mechanisms are needed to maintain cellular homeostasis and epithelial transport (29).