Fig. 6.
Steady-state activation and inactivation of ICa in Alaska blackfish ventricular cardiomyocytes at acclimation temperature (5°C or 15°C) and after acute exposure to 10°C. Steady-state activation and inactivation are compared between (A) 5°C- and 15°C-acclimated cardiomyocytes, (B) 5°C-acclimated cardiomyocytes recorded at 5°C and then acutely exposed to 10°C, (C) 15°C-acclimated cardiomyocytes recorded at 15°C and then acutely exposed to 10°C and (D) 15°C- and 5°C-acclimated cells acutely exposed to 10°C. The data from individual recordings were fit to the Boltzmann equation and the mean coordinates of the fitted curves are plotted (see Materials and Methods). Steady-state inactivation (SSI) curves decrease sigmoidally from 1, while steady-state activation (SSA) curves increase sigmoidally from 0. The shaded areas below the two curves represents the window current (WC) of ICa. Values are means ± S.E.M. Asterisks (*) indicate a statistically significant difference (P<0.05) at a specific voltage (unpaired t-tests for panels A and D; paired t-tests for panels B and C). N values are detailed in Table 4.