[Light-induced changes in activity of Na, K-ATPase from the retinal photoreceptors of vertebrates: possible mechanism].

The mechanism of light-induced changes in the activity of Na,K-ATPase from plasma membranes (PM) of photoreceptor cells was studied in vitro. Illumination resulted in inhibition of the ATPase activity and an increase of 18O exchange between water and Pi. The maximum light effect was revealed when the PM contained both the inner segments of the rods (RIS) and rod outer segments (ROS) of the photoreceptor cells. Lipid peroxidation stimulated by the FeSO4+ascorbate system induced a decrease of the ATPase activity. Antioxidants (ionol, Na2SeO3, vitamin E) prevented the effect of the lipid peroxidation products on NA,K-ATPase and the photoinduced changes of the enzyme activity. It is supposed that the photoinduced changes of the Na,K-ATPase activity in vitro are due to lipid peroxidation of photoreceptor PM.