Recovery from swelling of hepatocytes and selected other epithelia is triggered by intracellular Ca 2؉ release from the endoplasmic reticulum, which leads to fluid and electrolyte efflux through volume-sensitive K ؉ and Cl ؊ channels. The aim of this study was to determine the

Cell volume recovery in response to swelling requires reorganization of the cytoskeleton and fluid efflux. We have previously shown that electrolyte and fluid efflux via K ؉ and Cl ؊ channels is controlled by swelling-induced activation of phospholipase C␥ (PLC␥). Recently, integrin engagement has been suggested to trigger responses to swelling through activation of Rho family GTPases and Src kinases. Because both PLC␥ and Rho GTPases can be regulated by Src during integrin-mediated cytoskeletal reorganization, we sought to identify swelling-induced Src effectors. Upon hypotonic challenge, Src was rapidly activated in transient plasma membrane protrusions, where it colocalized with Vav, an activator of Rho GTPases. Inhibition of Src with PP2 attenuated phosphorylation of Vav. PP2 also attenuated phosphorylation of PLC␥, and inhibited swelling-mediated activation of K ؉ and Cl ؊ channels and cell volume recovery. These findings suggest that swelling-induced Src regulates cytoskeletal dynamics, through Vav, and fluid efflux, through PLC␥, and thus can coordinate structural reorganization with fluid balance to maintain cellular integrity.

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