Electrophysiological effects of propafenone in untreated and propafenone‐pretreated guinea‐pig atrial and ventricular muscle fibres
Why the study?
Does propafenone alter electrophysiological properties in untreated and propafenone-pretreated guinea-pig atrial and ventricular muscle fibres?
Population
Guinea-pig isolated atrial and ventricular muscle fibres from untreated animals and animals pretreated with…
Comparison
Propafenone (10 to 10 M) applied in vitro, and… vs Untreated guinea-pig atrial and ventricular…
Design
Preclinical
Follow-up
28 days (pretreatment duration)
Authors
Discussion
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Implication
Animal data support multi-class antiarrhythmic actions in guinea-pig models; leaves open translation to human arrhythmia management.
Key Points
- To evaluate the electrophysiological effects of acute and chronic propafenone exposure in isolated guinea-pig atrial and ventricular muscle fibers.
- Isolated atrial and ventricular muscle fibers were obtained from untreated guinea pigs and animals pretreated with propafenone at 3 or 10 mg kg⁻¹ daily for 28 days.
- Microelectrode techniques assessed responses to acute propafenone concentrations (10⁻⁷ to 10⁻⁴ M) on action potential amplitude, Vmax, resting membrane potential, duration, and refractory periods.
- In untreated tissues, acute propafenone caused a concentration-dependent decrease in rate, depressed action potential amplitude and Vmax, lowered resting membrane potential, and prolonged action potential duration and effective refractory period.
- Propafenone suppressed chronotropic responses to isoprenaline and depressed slow action potentials induced by isoprenaline and caffeine in depolarized papillary muscles.
- Chronic pretreatment at 10 mg kg⁻¹ significantly prolonged ventricular action potential duration compared to untreated controls or the 3 mg kg⁻¹ group, whereas 3 mg kg⁻¹ pretreatment showed action potential characteristics similar to untreated controls.
Structured PICO
Does propafenone alter electrophysiological properties in untreated and propafenone-pretreated guinea-pig atrial and ventricular muscle fibres?
P
Population
Guinea-pig isolated atrial and ventricular muscle fibres from untreated animals and animals pretreated with propafenone (3 and 10 mg kg-1 for 28 days)
I
Intervention
Propafenone (10(-7) to 10(-4) M) applied in vitro, and in vivo pretreatment with propafenone (3 and 10 mg kg-1 for 28 days)
C
Comparator
Untreated guinea-pig atrial and ventricular muscle fibres
O
Outcome
Electrophysiological properties including action potential amplitude, Vmax, resting membrane potential, action potential duration (APD), and effective refractory periodsurrogate
Propafenone exhibits class I, II, and IV antiarrhythmic actions in guinea-pig cardiac muscle, with chronic pretreatment also revealing class III actions (APD prolongation).
Cite This Study
Delgado et al. (1985) studied this question.