Fig. 3. (A) Diagram of the reproductive system of Aplysia showing the sites tested for localization of the effect of NO. (B) Analysis of the effect of the NO donor application to the abdominal ganglion. (i) Effect of application of the NO donor on the activity recorded extracellularly using a suction electrode placed on the cut pleural-abdominal connective, close to the bag cells. The two traces are continuous. The stimulus did not elicit a bag cell after-discharge. (ii) Electrical stimulation of the connective (in the example shown, 7 V, 7 Hz, 5 ms pulse duration, maintained for 5 s) induced an after-discharge. The three traces are continuous. The recordings began a few seconds after the stimulus, since the same suction electrode was used for stimulation and recording. The stimulating electrode was removed from the tubing and the recording electrode was then inserted.