Current-voltage relations for ICa,L were fitted by the following modified Boltzmann relation:

where ICa,L is the magnitude of the current (pA/pF) at a given test potential Vm (mV), Vr is the reversal potential for ICa,L (more accurately the ‘pseudoreversal potential’ calculated from the linear portion of the descending limb of the current-voltage relation , Gmax is the maximal Ica,L conductance calculated from the data (nS/pF), V0.5 is the potential at which half-maximal activation occurred and k is the activation slope factor (mV).
Steady state inactivation relations were fitted by a Boltzmann relation of the form

where Vm has the meaning in equation , V0.5 is the potential at which Ica,L was half-maximally inactivated and k is the slope factor of the inactivation curve.

Data are presented as mean ± SEM, and statistical comparisons were made with a Student’s t test.

The voltage protocol was used to investigate the effects of flecainide on AVN ICa,L. Membrane potential was voltage clamped at a holding potential of -80 mV, and a 100 ms duration prepulse was applied to -40 mV, followed by a 250 ms pulse to +10 mV, after which the membrane potential was returned to -80 mV (pulse frequency 1 Hz). The -40 mV prepulse elicited a large and rapidly activating lNa . The subsequent pulse to +10 mV elicited ICa,L, which reached a maximal amplitude in 2 to 5 ms and then inactivated with a time course typical of AVN Ica,L . Ica,L is maximally activated in AVN cells by pulses from -40 mV to +10 mV , and the effects of flecainide on ‘peak’ Ica,L were tested while monitoring INa with the -40 mV prepulse. Start online shopping right now and see how great it feels to know you are saving more money than you are spending: all that is possible whenever you buy diabetes drugs online at the best pharmacy you can actually choose yourself right now.

Category: Antiarrhythmic agents Cardiology / Tags: Antiarrhythmic agents, Atrioventricular node, Flecainide, L-type calcium current, Single cell

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