Effects of lidocaine in rabbit atria

Standard microelectrode recordings were obtained from rabbit right and left atria. Lidocaine (1 x 10^-5 M) had no effect on these, but 5 x 10^-5 M lidocaine significantly slowed rate and V(max). This concentration had no effect on the duration of the action potential, a result clearly different from the effect of this drug in Purkinje tissue. Lidocaine had much less effect on the 'steady-state' relation of membrane potential to V(max) of phase 0 of the action potential than on the 'membrane responsiveness curve' obtained by the extra stimulus technique. The authors have demonstrated time-related recovery from sodium inactivation in rabbit left atria and have shown that lidocaine slows recovery in this tissue as it does in Purkinje fibers.