Fig. 5. Effects of isoflurane on steady-state activation of cardiac calcium channel currents. Activation curves for L- (circle) and T-type (square) Ca2+channel currents in atrial (left ) and ventricular myocytes (right ) were obtained by dividing the peak current recorded during each test potential by the driving force (see Methods). The normalized peak conductance for each calcium channel is plotted against test potential before (control; open symbols) and after isoflurane (0.9 mm; filled symbols). The dotted curves represent the Boltzmann fits to the data.