Fig. 3.
Slow responses to 5-HT are inhibited by pertussis toxin (PTx). Preparations were superfused with PTx (1.0 μg/ml) for 6 hr. Control preparations were superfused for an equivalent period of time but in the absence of PTx. To control for nonspecific effects of prolonged superfusion, responses of AH/type 2 cells to 5-HT were compared with the similar responses of the same cells to forskolin in the presence or absence of PTx. The graph shows the ratio of the 5-HT to the forskolin response for control and PTx-treated preparations.