Effect of norepinephrine on inhibition of mouse brain (Na+ + K+)-stimulated, (Mg++)-dependent, and (Ca++)-dependent ATPase activities by ethanol.

Norepinephrine (0.1 mM) has been reported to "sensitize" (Na+ + K+)-ATPase activity of rat brain homogenates to inhibition by ethanol. The present study extends these investigations to the mouse and includes other ATPase activities. We measured the effects of norepinephrine on the sensitivity of ethanol-induced inhibition of (Na+ + K+)-stimulated (E.C. 3.6.1.3), (Mg++)-dependent (E.C. 3.6.1.4) and (Ca++)-dependent ATPase activities. Whole forebrains from C57BL/6J mice were homogenized and assayed in vitro for ATPase activity using standard conditions. Ethanol (0.125-2.0 M) caused a dose-dependent inhibition of all three ATPases. Norepinephrine (0.1 mM) had no appreciable effect on ethanol's inhibition of (Na+ + K+)-stimulated or (Ca++)-dependent ATPase activities, but slightly antagonized ethanol's effect on (Mg++)-ATPase. These results suggest that norepinephrine has little effect on the sensitivities of specific ATPases to ethanol inhibition in mouse brain.