The Na+/H+ exchanger modulates the fibrogenic effect of oxidative stress in rat hepatic stellate cells

Background/Aims: Oxidative stress is associated with liver fibrosis in who and with hepatic stellate cell (HSC) activation in vitro, but the intracell ular mechanisms mediating these effects are mostly unknown, The Na+/H+ exch anger plays a key role in regulating the cell cycle, and is involved in HSC proliferation, Its role in different HSC features, such as collagen accumu lation, is still unknown, We thus evaluated if the Na+/H+ exchanger modulat es the fibrogenic effect of oxidative stress in rat HSC. Methods: HSC were incubated with 0.1 mM ferric nitrilotriacetate complex (F eNTA), Intracellular hydroperoxides and malonildialdehyde (MDA) levels in t he culture media were measured by the dichlorofluorescein and TBARS method, respectively, Intracellular pH and Na+/H+ exchanger activity were measured using the fluorescent dye BCECF. Cell proliferation was measured by immuno histochemistry for bromodeoxyuridine incorporation, Collagen type I accumul ation in the culture media was measured by ELISA. Results: HSC incubation with FeNTA resulted in a significant production of intracellular hydroperoxides and MDA, associated with increased Na+/H+ exch ange activity and baseline intracellular pH (pHi). Exposure of HSC to FeNTA significantly enhanced the number of proliferating HSC and collagen type I levels in the culture medium, All these effects were reversed by the antio xidant resveratrol and by the Na+/H+ exchanger inhibitor amiloride, Conclusions: This study indicates that the Na+/H+ exchanger might represent a common mediator of the different effects induced by oxidative stress on HSC, The reduction in cell proliferation and collagen synthesis induced by amiloride could represent a new therapeutic challenge in liver fibrosis.