Abstract
To sense an environmental change such as osmotic stress is crucial for cells to survive and adjust to a new environment. In the epithelium of distal nephron, basolateral hypotonic stress is known to stimulate epithelial Na+ channel (ENaC)-mediated Na+ reabsorption for recovery of normal plasma osmolality without hormonal regulation. On the other hand, hypotonic stress causes drastic cell volume changes; initial cell swelling followed by regulatory volume decrease (RVD). Recently an increase in membrane tension by the initial cell swelling is considered to play an important role in conversion of extracellular physical stress to intracellular chemical signals. In this review, we focus our study on possible roles of plasma membrane itself and membrane proteins such as mechano-sensitive (MS) ion channels and growth factor receptors in sensing extracellular osmolality (hypotonic stress) and leading to regulation of Na+ reabsorption.
