Hydrogen Peroxide Stimulation of Active Sodium Transport in Isolated Frog Skin: Indicative of a Possible Prostaglandin Interaction

Abstract

The influence of reactive oxygen metabolites on ion transport across the plasma membrane was investigated by measuring the effects of hydrogen peroxide (H2O2) on short-circuit current (SCO in isolated frog skin. Addition of H2O2 to the basolateral (inner) membranes of the polarised epithelial cells induced a dose-dependent stimulation of SCC with a half maximal stimulating concentration of 41üM H2O2. This stimulation could be blocked by 100μM amiloride in the apical (outer) solution, showing that H2O2 induced a specific activation of the active transport of sodium (Na+). The effect of H2O2 was inhibited in skins pretreated with 5μM indomethacin, implying the involvement of prostaglandins in the response. Furthermore, the effect of H2O2 was inhibited in the presence of 0.1mM quinacrine, indicating that the activation of the cyclo-oxygenase pathway is dependent on phospholipase A2 activity. The present data demonstrate that H2O2 in low concentrations (1μM-1mM) induced a specific stimulation of active Na+ transport due to activation of prostaglandin synthesis. An acute toxic effect on the electrophysiological parameters was noted after the addition of higher H2O2 concentrations (10–100mM). This effect resulted in a non-specific increase in the ion permeability of the epithelium, probably as a result of membrane damage due to lipid peroxidation.