Uncompetitive stimulation of rat brain Na-K ATPase activity by rapid eye movement sleep deprivation

Abstract

Rapid eye movement sleep deprivation is associated with an increase in Na-K ATPase activity. In order to understand the possible biochemical mechanism of this increase, the kinetics of Na-K ATPase was studied. Although the enzyme activity increased after the deprivation, the catalytic efficiency of the enzyme remained unaltered. The rapid eye movement sleep deprivation increased both the V_max and the K_m suggesting an uncompetitive stimulation of the enzyme. While increase in norepinephrine resulted in an increased V_max, that of calcium increased the K_m. Since an increase in norepinephrine has been suggested after deprivation, the increased V_max is attributed to increased norepinephrine level following deprivation. However, since rapid eye movement sleep deprivation is reported to be associated with a decrease in calcium levels, the increase in K_m following deprivation may be attributed to changes in factor(s) other than calcium.