Figure 3. The dose-response relationship of 51W89 generated by ordinary least-squares regression of the probit of maximum twitch suppression versus the common logarithm of the 51W89 dose. The dose- response equation, based on the plotted data, is probit (T1suppression)- 7.5 (log Dose)+ 11.5. ED50is 0.029 mg *symbol* kg sup -1 51W89, and ED95is 0.048 mg *symbol* kg sup -1 51W89.