Figure 5. Voltage-dependent inhibition of Na sup + current by methoxamine and anesthetics. Effect of methoxamine in the presence of either halothane or isoflurane are shown after maximal anesthetic effect. Panel A represents average depressant effects of peak I^Naduring methoxamine (100 micro Meter, n = 6), methoxamine with halothane (1.2 mM, n = 7) and methoxamine with isoflurane (1.0 mM, n = 6) during 50- ms test pulses to -20 mV from a V^Hof -110 mV. Panel B summarizes average depressant effects of peak I^Naduring methoxamine (10 micro Meter, n = 16), methoxamine with halothane (1.2 mM, n = 6) and methoxamine with isoflurane (1.0 mM, n = 6), obtained from a V^Hof -80 mV. Values are mean +/- SEM. +Significantly different versus control, *Significantly different versus methoxamine (10 micro Meter) in the absence of anesthetics, #Significantly different from steady-state I^Naamplitude after halothane exposure, $Significantly different from steady-state I^Naamplitude after isoflurane exposure.