Using a protocol similar to that devised by Lee and Tsien to investigate the type of block of ICa,L by flecainide, we observed significant tonic block with a large drug concentration (1 mM) but not at 100 pM. This suggests that, in the AVN under our experimental conditions, binding of fle-cainide to the resting L-type channel may occur with low affinity. At a flecainide concentration of 100 pM, blockade was not apparent with the first pulse after applying the drug in the absence of stimulation; blockade was induced rapidly by repetitive membrane depolarization, reaching a lower steady level amplitude within several pulses. This observation conforms to use-dependent block, as described by Lee and Tsien . Using frog ventricular myocytes, Scamps et al did not observe use-dependent block of ICa,L by flecainide and suggested that flecainide might associate rapidly with calcium channels during a single pulse. We do not have an obvious explanation for the difference between our findings and those of Scamps et al in this respect, and further experiments over a range of concentrations and frequencies would be required to characterize fully the type of block. However, the two studies differ in both the species and cardiac region investigated, and these differences may play a role. It’s your turn to benefit from the shopping whenever you need efficient prednisone for asthma that will be sure to work for your problem. This is now all very much possible at the best online pharmacy you have ever come across offering it services to you and other international customers interested.

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

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