Calcium reverses lidocaine-induced conduction block in rat fimbria in vitro

1. We have tested the effect of changed concentrations of Ca2+ upon lidocaine-induced conduction block in rat fimbria. 2. With bath [Ca2+] of 0.25 mM, 0.5 mM lidocaine reduced the amplitude of the compound action potential to 20.2% +/- 2.25% of baseline (n = 5). 3. On changing the bath [Ca2+] to 4.4 mM, with no change in lidocaine concentration, the compound action potential increased by 33.5 +/- 6.5%. 4. In the absence of lidocaine, changing bath [Ca2+] had opposite effects. These results replicate findings by others in peripheral nerve.