Key result
Ambasilide prolonged action potential duration at rapid pacing rates independent of extracellular potassium, whereas dofetilide's effect was reduced with increasing pacing rate and high potassium.
Why the study?
Do ambasilide and dofetilide prolong action potential duration in guinea pig right ventricular papillary muscle at different extracellular potassium concentrations and pacing frequencies?
Do ambasilide and dofetilide prolong action potential duration in guinea pig right ventricular papillary muscle at different extracellular potassium concentrations and pacing frequencies?
In a preclinical model, ambasilide maintains its action potential prolonging effects at rapid pacing rates and altered potassium concentrations better than dofetilide, suggesting potential utility in treating tachyarrhythmias under these conditions.
Ambasilide preserves APD prolongation at rapid rates independent of [K+]e in vitro; leaves open clinical antiarrhythmic relevance versus dofetilide.
We studied the effect of two new class II antiarrhythmics, ambasilide and dofetilide, on the action potential duration (APD) of guinea pig right ventricular papillary muscle at different extracellular potassium concentrations ([K+e]) and pacing frequencies. Under normal [K+e], both drugs significantly prolonged APD90 (APD at 90% repolarization) at 0.5 Hz. The effect of ambasilide was well preserved at rapid pacing rates, independent of [K+e]. The effect of dofetilide was markedly reduced with increasing pacing rate, especially in high [K+e]. Therefore, ambasilide may be useful in treating tachyarrhythmias in normal, as well as in altered [K+e] conditions.
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Gjini et al. (1996) studied this question. Ambasilide and dofetilide was evaluated on Action potential duration (APD90). Ambasilide prolonged action potential duration at rapid pacing rates independent of extracellular potassium, whereas dofetilide's effect was reduced with increasing pacing rate and high potassium.
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