Concentration dependence of Nav1.4 inhibition by inhaled anesthetics. Normalized peak INa values from a holding potential of −120 mV were fitted to the Hill equation to yield IC50 values (±SE) and Hill slopes. IC50 values differed from each other by sum-of-squares F-test (P < 0.05). □, Halothane; ▲, Isoflurane; ▽, Sevoflurane; ◆, Enflurane; ○, Desflurane.