Ajmaline-induced block of sodium current in rat ventricular myocytes

0212137 - UT-L 20020083 RIV CZ eng J - Journal Article
Bahníková, M. - Matějovič, P. - Pásek, Michal - Šimurdová, M. - Šimurda, J.
Ajmaline-induced block of sodium current in rat ventricular myocytes.
Scripta Medica. Roč. 75, č. 4 (2002), s. 169-178. ISSN 1211-3395
Institutional research plan: CEZ:AV0Z2076919
Keywords : ajmaline-induced * sodium current
Subject RIV: BO - Biophysics

The aim of the present study was to explore concentration-, voltage- and frequency-dependence of the sodium current (INa) block induced by ajmaline in enzymatically isolated rat ventricular myocytes. Voltage clamp experiments in whole-cell patch-clamp arrangement were performed on 32 cells. The blocking effect was evaluated in the range of concentrations between 0.3 and 5000 mmol/l at room temperature. The level of block was concentration-dependent and the effect was fully reversible. Pooled data analysis (18 cells and 25 measurements) resulted in EC50 = 8.2 1.5 mmol/l and the Hill coefficient of 0.62 0.08. The voltage- and frequency-dependence of the drug effect was analysed at 3 mmol/l. The block appeared to be voltage-dependent but frequency-independent in contrast to propafenone (0.2 mmol/l). An analysis of the rate of block level variations in response to voltage steps revealed substantial differences between kinetics of the block development in both drugs that corresponded well with the observed difference in the frequency response.
Permanent Link: http://hdl.handle.net/11104/0107686