Figure 3.

(A) Conduction across the LA and along the PV in a preparation driven by 5 Hz electrical stimulation applied to the base of the LAA. In 3 × 10⁻⁸ M cirazoline conduction was maintained across the LA (E1 to E4) while conduction along the PV (E5 to E8) was lost. (B) Effect of cirazoline upon the conduction velocity of electrical signals evoked by stimulation in the LAA. The application of cirazoline led to the progressive reduction of conduction velocity (measured as the time taken for the signal to pass between 2 adjacent electrodes) prior to the loss of the electrical signal between E5 to E8 in the distal PV. This decrease was less pronounced at the junction between PV and LA (between E5 to E3) and was not observed in the LA (between E3 to E1) (n = 5, **p < 0.01, ***p < 0.001 vs 0 min, standard error bars have been omitted for clarity). (C) When electrical stimulation was applied to the distal PV, cirazoline (3 × 10⁻⁸ M) blocked conduction not only along the vein (E8 to E5) but also across the LA (E4 to E1).