Fig. 3. Nicotine (open circles) and metanicotine (closed circles) induced release of norepinephrine from synaptosomes prepared from dorsal spinal cord in the presence (top ) or absence (bottom ) of the norepinephrine reuptake inhibitor desipramine (10−5m). Each point represents the mean ± SE of seven experiments in duplicate. *P < 0.05 compared with control without nicotine. φP < 0.05 compared with nicotine.