Fig. 6. Effects of L-type voltage-gated Ca²⁺ channel blockers on responses to proctolin and F₂. (A) OOM was perfused with nifedipine (0.1 mmol l^-1) saline for 30 min before 30 s pulses of PR and F₂ (0.1 µmol l^-1 each). (B) Verapamil (0.1 mmol l^-1) was perfused for 31 min before 30 s pulses of PR and F₂ (0.1 µmol l^-1 each). (C) CdCl₂ (1 mmol l^-1) greatly attenuated tetani, but did not prevent contractures following 30 s pulses of PR (0.1 µmol l^-1) or F₂ (10 nmol l^-1).