rabbit atrioventricular nodal myocytes (part 10)

In addition to testing the effects of flecainide on Ica,L elicited by pulses to +10 mV, test pulses were applied to a range of membrane potentials (in 10 mV increments from -40 mV after the prepulse from -80 to -40 mV [Figure 3B, inset]), before and after exposure to flecainide 100 ^M, to investigate any voltage-dependent effects of this agent. current-voltage relations for Ica,L were constructed in the absence and presence of flecainide.
Representative current-voltage relations in Tyrode’s solution and after application of 100 ^M flecainide are shown in Figure 3B (similar results were observed in each of seven cells). The control current-voltage relation, between -40 and +40 mV, was well described by the Boltzmann fit described in equation 2 (Methods), with peak Ica,L predicted at +10 mV, and V0.5 and k values of -2.5 mV and 6.2 mV, respectively. After a 2 min exposure to flecainide, the effect reached a steady state. ICa,L magnitudes in the presence of flecainide are plotted on Figure 3B. With a pulse to -20 mV, ICa,L was only slightly inhibited by flecainide, but at other test potentials, the current-voltage relations in the two experimental conditions clearly diverged. In the presence of flecainide, the peak ICa,L (calculated by the Boltzmann fit) was shifted in the negative direction (to +5 mV) and V0.5 and k values were -5.8 mV and 5.7 mV, respectively. For seven cells, under control conditions the mean V0.5 value was -3.1±1.1 mV and k was 6.5±0.3 mV. Buy cheap drugs online fast – canadian cialis for you to enjoy a reliable pharmacy.

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

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