The effects of flecainide on the voltage-dependent inactivation properties of ICa,L were also investigated. The steady state voltage-dependent inactivation relation for ICa,L inactivation was determined in each of five cells before and during exposure to flecainide 100 pM. The voltage protocol for these experiments is shown in Figure 4 (inset). From the holding potential of -80 mV, a 1 s conditioning pulse was applied to potentials between -100 mV and +60 mV, immediately followed by a 250 ms test pulse to +10 mV. ICa,L amplitude activated by the test pulse to +10 mV was measured following each conditioning pulse and expressed for each cell as a proportion of the maximal ICa,L recorded.To remove any contamination by INa or T-type calcium current, which might be activated following a prepulse to a negative membrane potential, a sodium-free, 40 |iM nickel-containing solution was used. Inactivation variables for ICa,L before and after addition of flecainide 100 |jM were obtained and fitted by the Boltzmann fit in equation (Methods). Figure 4 shows a typical result. At each membrane potential the inactivation variables are very similar in the two conditions. For this cell, V0.5 was -25.1 mV and k was 7.39 under control conditions, while in the presence of flecainide, V0.5 was also -25.1 mV and k was 6.04 mV. For five cells, the mean values were V0.5 -23.5±1.7 mV and -23.7±1.6 mV, k 6.7±0.6 mV and 6.8±0.8 mV for control and flecainide-containing solutions, respectively. Thus, under the experimental conditions used in this study, there appeared to be little effect of flecainide on the steady state voltage-dependent inactivation properties (P>0.1 for both V0.5 and k). There is always a great pharmacy waiting for you to visit and purchase the amount of medicine you need, be that ampicillin antibiotic or any other one. You can see that all for yourself once you visit, enjoying most advantageous deals ever.

Inhibition of L-type calcium current by flecainide in isolated single rabbit atrioventricular nodal myocytes

Figure 4 Steady state inactivation relation for an atrioventricular node cell in the two experimental conditions (control [normal Tyro-de’s solution], flecainide [100 ^M]). In each of five such cells the inactivation curve was affected little by exposure to flecainide. Inset Voltage protocol used: 1 s prepulses to different potentials were followed by a 250 ms test pulse to +10mV. Inactivation curves werefit-ted to data as described in equation of the Methods 

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

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