Fig. 3. Changes in percent of current decay by halogenated compounds in PC12 cells. The percent decay of the current during agonist application defined by the following equation:%current decay = (peak current − nondesensitized current)/peak current × 100. The percent of current decay in the presence of the halogenated agents was normalized to the average of the values obtained before and after the addition of the agents (% current decay ratio). The ratio for 0 MAC represents control currents measured by comparing the value of the second response, with the average of the first and third responses in the experiments in which nicotine alone was applied successively three times. The number of determination was the same as in figure 2. *Significant difference from control with P < 0.01.