Fig. 4. Depression of spontaneous action potential firing by 0.2 μm etomidate in wild type (white) and β3(N265M) mutant (black) preparations. Average spike rate (wild type 65.39 ± 5.42%; mutant 30.86 ± 8.15%; P < 0.05) and burst rate (wild type: −11.92 ± 11.36%; mutant: −0.25 ± 6.45%; P > 0.05) are counted over 180 s. Spike rate 200 to 1000 ms (wild type 71.24 ± 5.54% versus mutant 27.25 ± 19.6%; P < 0.05) is the discharge rate between 200 and 1000 ms after the beginning of a burst.