Article date: November 1989
By: Hiroyasu Satoh, Masaaki Ishii, Keitaro Hashimoto in Volume 98, Issue 3, pages 827-832
Electrophysiological effects of NIK‐244 (ethacizin), a novel class I antiarrhythmic drug, were compared with flecainide in canine ventricular muscle by use of conventional microelectrode techniques.
At concentrations of 10−6m. or higher, NIK‐244 depressed the maximum rate of rise of depolarization () significantly in a concentration‐dependent manner. Also, the resting potential was depolarized at 10−5m. NIK‐244 did not have any effect on the other action potential parameters or on the effective refractory period.
Flecainide significantly decreased at 3 × 10−6m. or higher and the resting potential was depolarized at 10−5m. Like NIK‐244, flecainide did not affect other action potential parameters.
NIK‐244 and flecainide caused a use‐dependent block of , and the rates of onset of inhibition at 3 Hz stimulation were 0.014 ± 0.002 AP−1 at 2 × 10−6m. NIK‐244 and 0.021 ± 0.012 AP−1 at 10−5m. flecainide. Under the same conditions, the time constants of the recovery from use‐dependent block were 27.1 ± 13.3 s and 12.2 ± 2.5 s for NIK‐244 and flecainide, respectively.
These results suggest that NIK‐244, like flecainide, should be classified as a slow kinetic drug and as Ic.
Electrophysiological effects of NIK‐244 (ethacizin), a novel class I antiarrhythmic drug, were compared with flecainide in canine ventricular muscle by use of conventional microelectrode techniques.
At concentrations of 10−6m. or higher, NIK‐244 depressed the maximum rate of rise of depolarization () significantly in a concentration‐dependent manner. Also, the resting potential was depolarized at 10−5m. NIK‐244 did not have any effect on the other action potential parameters or on the effective refractory period.
Flecainide significantly decreased at 3 × 10−6m. or higher and the resting potential was depolarized at 10−5m. Like NIK‐244, flecainide did not affect other action potential parameters.
NIK‐244 and flecainide caused a use‐dependent block of , and the rates of onset of inhibition at 3 Hz stimulation were 0.014 ± 0.002 AP−1 at 2 × 10−6m. NIK‐244 and 0.021 ± 0.012 AP−1 at 10−5m. flecainide. Under the same conditions, the time constants of the recovery from use‐dependent block were 27.1 ± 13.3 s and 12.2 ± 2.5 s for NIK‐244 and flecainide, respectively.
These results suggest that NIK‐244, like flecainide, should be classified as a slow kinetic drug and as Ic.
DOI: 10.1111/j.1476-5381.1989.tb14611.x
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