Figure 3.

The effect of NMDA (20 mM), EtOH (100 mM), bicuculline (Bic) (10 μM), naltrexone (Nalt) (10nM), and their combinations on NOS activity measured by the ¹⁴C-citrulline method. Because activation of the enzyme yields equimolar release of NO and citrulline, the results are plotted as NO release. **, P < 0.01, as compared versus control column; +, P < 0.05 as compared versus NMDA column and NMDA+EtOH+Nalt+Bic column. n = 9 for each column (Student-Neuman-Keul test). NMDA increased NOS activity, EtOH blocked it, and Nalt+Bic reverted this inhibition.