Fig. 6. (A ) Verapamil elicited dose-dependent increases in the duration of local anesthesia. Baseline tail-flick latencies to radiant-heat nociception were obtained before injecting vehicle or verapamil. At the indicated times, the animals were tested for local anesthesia. The groups consisted of vehicle (open circle, solid line) or verapamil (filled triangle, 4.1 mm; filled circle, 16.0 mm). *P < 0.05 compared with baseline latency; ‡P < 0.05 compared with corresponding vehicle time point. (B ) Verapamil elicited dose-dependent local anesthesia. Baseline tail-flick latencies were obtained before injecting mice with verapamil (filled circle, solid line). The mice were tested for local anesthesia 15 min later. The dose–response curve represents 30 mice. %MPE = percentage of maximum possible effect.