Key result
N-acetylprocainamide affected the maximum upstroke velocity of the cardiac action potential at lower concentrations than required to affect half-decay time, displaying typical class IA antiarrhythmic behavior.
Why the study?
N-acetylprocainamide is widely described as a pure class III antiarrhythmic, but conflicting evidence in other species suggests it affects cardiac Na+ channels.
Does N-acetylprocainamide affect the maximum upstroke velocity and half-decay time of the cardiac action potential differently than procainamide in guinea pig papillary muscle?
Population
Isolated right papillaris magnus of the guinea pig heart
Comparison
Procainamide vs N-acetylprocainamide
Design
Preclinical ex vivo study
Authors
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Challenges view of NAPA as pure class III; animal data leave open human relevance.
Does N-acetylprocainamide affect the maximum upstroke velocity and half-decay time of the cardiac action potential differently than procainamide in guinea pig papillary muscle?
NAPA acts as a class IA antiarrhythmic in guinea pig myocardium, challenging the widely accepted concept that it is a pure class III agent.
Sigler et al. (2023) studied this question. N-acetylprocainamide (NAPA) vs. Procainamide (PA) was evaluated on Maximum upstroke velocity (Vmax) and half-decay time (HDT) of the cardiac action potential. N-acetylprocainamide affected the maximum upstroke velocity of the cardiac action potential at lower concentrations than required to affect half-decay time, displaying typical class IA antiarrhythmic behavior.
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