Fig. 1. Voltage-dependence of I_Na in ventricular myocytes of crucian carp, rainbow trout and burbot hearts. Currents were elicited from a holding potential of –120 mV with 60 ms depolarising pulse between –100 and +70 mV (top). (A) Representative recordings of I_Na from cold-acclimated (c.a.) fish at +4°C. (B) Results shown as means ± S.E.M. (N=9–16). I–V curves from warm-acclimated (w.a.; closed symbols) and c.a. (open symbols) fish are superimposed to allow direct comparisons between acclimation groups at physiological body temperatures (+4°C/+18°C) and at the common experimental temperature (11°C). See Materials and methods for details.