Fig. 2. The effect of 75% N²O on the number of c-Fos–positive cells (mean ± SD) in each laminae of the spinal cord at the lumbar level in α¹adrenoceptor–positive and –negative cells; analysis of the data in table 3that are based on a total of eight animals. Open column indicates the number of c-Fos–positive cells in the air-exposed group (control). Closed column indicates the number of c-Fos–positive cells in the N²O-exposed group. *P < 0.05 versus  control.