Peroxynitrite induced decrease in Na(+), K(+)-ATPase activity is restored by taurine.

摘要

AIM: Peroxynitrite (ONOO(-)) is a powerful oxidant shown to damage membranes. In the present study, the effect of taurine on changes of liver plasma membrane Na(+), K(+)-ATPase induced by ONOO(-) was investigated. METHODS: Liver plasma membrane was exposed to ONOO(-) with or without taurine. Na(+), K(+)-ATPase activity and lipid peroxidation as thiobarbituric acid reactive substances (TBARS) levels were measured. RESULTS: Different concentrations of ONOO(-) (100, 200, 500, and 1 000 mumol/L) were found to decrease liver plasma membrane Na(+), K(+)-ATPase activity significantly. The depletion of enzyme activity was not concentration dependent. Effects of different concentrations of taurine on liver plasma membrane Na(+), K(+)-ATPase activity were also measured. Taurine did not cause any increase in enzyme activity. When plasma membranes were treated with 200 mumol/L ONOO(-) with different concentrations of taurine, a restoring effect of taurine on enzyme activity was observed. TBARS levels were also measured and taurine was found to decrease the elevated values. CONCLUSION: Taurine is observed to act as an antioxidant of ONOO(-) to decrease lipid peroxidation and thus affect liver plasma membrane Na(+), K(+)-ATPase by restoring its activity.