Fig. 3. Effect of the calmodulin inhibitor calmidazolium on ciliary beat frequency (CBF) in unidentified ciliary cells in culture. Application of 100 mmol l^–1 5-hydroxytryptamine (5-HT) produced a significant increase in CBF versus the saline control (asterisk: P<0.05, N=7 cells). Application of either 0.1% DMSO (N=7 cells) or 2 mmol l^–1 calmidazolium (Cal; N=12 cells) caused no change in CBF. When 2 mmol l^–1 Cal was co-applied with 100 mmol l^–1 5-HT, the calmodulin inhibitor blocked the stimulatory effect of 5-HT (N=9 cells).