Under the experimental conditions of this study, therefore, flecainide inhibited AVN Ica,L rapidly and reversibly. It is also evident from Figure 1A,B,c that flecainide reduced Ica,L in a dose-dependent fashion. An additional (and qualitative) observation was that Ica,L and INa appeared to show differential sensitivities to the drug. This is shown most clearly in Figure 1B – flecainide 100 ^M almost completely abolished INa in this cell, while reducing Ica,L only partially.
Five different doses of flecainide ranging from 10 ^M to 1 mM were applied to +10 mV by using the two-step protocol to elicit Ica,L. Figure 3A shows the mean fractional Ica,L inhibition plotted against drug concentration (on a logarithmic scale). From the data points alone, half-maximal inhibition of Ica,L by flecainide is predicted to occur in the range between 50 ^M and 100 ^M. To obtain a value for Kd for Ica,L block, the data were fitted with the Langmuir function given by equation 1 (Methods). The data were fitted by using a Kd of 63.4±8.2 ^M and a Hill coefficient of 1.3.

Inhibition of L-type calcium current by flecainide in isolated single rabbit atrioventricular nodal myocytes Buy best quality medications online at the pharmacy that will make sure your are happy with the prices and the quality of your glucophage diabetes whenever you need some treatment and have no idea where to get it.

Figure 3 A Dose-response relation for L-type calcium current (Ica,L) block by flecainide. Vertical axis represents ‘fractional block’ of Icci,l by flecainide (1.0 = total block; 0= no block), and the horizontal axis shows flecainide concentration plotted on a logarithmic scale. Five doses offlecainide between 10 цM and 1 mM were applied (numbers in brackets represent number of cells exposed to each dose). Data were fitted by equation 1 in the Methods section with Kd 63.4 ^M and Hill coefficient 1.3. B,C Voltage-dependent effects offlecainide on Ica,L. B Current-voltage relation for Ica,L in normal Tyrode’s solution and after application offlecainide 100 ^M (inset shows voltage protocol) by using 10 mV steps to test potentials between -40 and +40 mV). Curve-fits to current-voltage relations were obtained using equation , described in the Methods. C Degree of Ica,L block (vertical axis) plotted against test potential (horizontal axis; same cell as B). IFlec Flecainide current; Icontrol Control current

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

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