Figure 5A shows the results obtained with flecainide 1 mM (Figure 5Ai shows individual records from a single cell and Figure 5Aii the mean data from four cells). It is clear that the ICa,L elicited by the first pulse on resuming stimulation declined to 10% of the control amplitude and then showed a further decline over six pulses until the block was complete. At this concentration, therefore, flecainide appeared to show significant tonic or ‘resting’ inhibition of ICa,L. When similar experiments were performed with flecainide 100 |iM, however, there was no significant difference between control ICa,L and that elicited by the first pulse on resuming stimulation (Figure 5Bi). Over several pulses, ICa,L then declined to a steady level within four to five pulses. Similar results were obtained in each of the five cells tested (Figure 5Bii).

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

Figure 5 Investigation of the type block of the L-type calcium current (Ico,l) by flecainide. Control values ofIca,L amplitude were obtained by applying test pulses to +10 mV in normal Tyrode’s solution. Once Ica,L amplitude reached steady state, pulsing was discontinued, and flecainide was rapidly applied. After 45 s to 1 min, pulsing was resumed. A Results with flecainide 1 mM. Ai Ica,L before application of flecainide (control) and on resuming stimulation after exposure to flecainide 1 mM (pulses 1 and 5). Aii Mean data (n=4). Ica,L amplitude at each pulse is expressed as a proportion of the control. Withflecainide 1 mM, Ica,L attained only a small fraction of the control amplitude on the first pulse. B Results withflecainide 100 ^M. Bi Ica,L before application of flecainide (control) and on resuming stimulation after exposure (pulses 1 and6). Bii Mean data (n=5), plotted as a proportion of the control. At 100 ^M, there was little difference between control Ica,Land that elicited by pulse 1. current amplitude declined over several pulses to reach a steady amplitude   Your shopping for best quality medications is going to be pleasant and very affordable every time: make sure of it yourself when you visit the best pharmacy to buy cipro antibiotic as this is the kind of experience every patient is looking forward to.

 

 

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

Leave a Reply

Your email address will not be published. Required fields are marked *

CAPTCHA image
*