Fig. 6. Frequency dependence of local anesthetic induced block was analyzed at three different interpulse durations (100 ms [ triangle ], 300 ms [ square ], and 1,000 ms [ circle ]). The remaining current under the influence of the local anesthetic agents in the steady state phase at the end of the test potential was normalized to control values. The normalized current values were plotted against a time axis according to the different interpulse durations. Inhibition of Kv1.1 channels was not frequency dependent, because the frequency of the depolarizing pulse did not significantly influence local anesthetic–induced inhibition. ( A ) Dextrobupivacaine, ( B ) levobupivacaine, ( C ) racemic bupivacaine, ( D ) dextroropivacaine, ( E ) levoropivacaine, and ( F ) racemic mepivacaine.