Fig. 8. Effects of the glutamatergic antagonists MK-801 and Joro spider toxin (JSTX) on excitatory junctional potentials (EJPs) evoked on valve muscle cells of the anterior median artery (AMA) by stimuli applied to the valve excitatory nerve (VE). Three (A) and five (B) sweeps triggered by stimulus pulses were superimposed. (A) 3 min after the onset of perfusion with MK-801 (1 mmol l^-1), EJPs were almost abolished. After washing with saline, EJPs recovered. (B) 25 min after bath application of JSTX (concentration was calculated to be 5 µmol l^-1), the amplitude of each of five EJPs was diminished by more than half. The effect of JSTX did not reverse within one hour.