Figure 2. Effects of calyculin A on the voltage dependencies of activation and steady-state inactivation.

A, normalized plots of the mean (±s.e.m., n= 7, 3) voltage dependence of I_Ca before (▪) and after (▴) 5 min of exposure to 100nm calyculin A. The current at each test potential was normalized to the maximum current from the experiment and the average values were plotted versus test potential. The plots are from the data used for Fig. 1A and B). Normalized plots of the voltage dependencies of activation (open symbols) and steady-state inactivation (filled symbols) from cells before (▪, □) and after (▴, ▵) 100nm calyculin A (n= 8, 3). Voltage dependence of activation was determined from the I_Ca–V relationships shown in Fig. 1A. The conductance (g) at each potential was calculated as g=I_Ca/(E_m−E_rev), where E_m is the test potential and E_rev the reversal potential, as determined from the I_Ca–V plot. The conductance was then normalized to the maximal conductance obtained during the experiment. Voltage dependence of steady-state inactivation was determined from data in Fig. 1B. The current at each holding potential was normalized to the largest current recorded during the experiment. The average values for each were plotted versus holding potential.