What does this research mean for the field?

During myocardial ischemia, abrupt cell-to-cell electrical uncoupling, ischemic contracture, and the secondary rise of extracellular potassium are closely associated temporally, and calcium entry blockade with verapamil delays the onset of these events without altering their qualitative relationship. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

This research examines how passive electrical properties and extracellular potassium levels affect mechanical activity in rabbit ventricular muscle during ischemia.

June 1, 1990Circulation Research

Passive electrical properties, mechanical activity, and extracellular potassium in arterially perfused and ischemic rabbit ventricular muscle. Effects of calcium entry blockade or hypocalcemia.

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Why the study?

Does verapamil or hypocalcemia alter passive electrical properties, mechanical activity, and extracellular potassium in arterially perfused and ischemic rabbit ventricular muscle?

Population

Isolated rabbit papillary muscle

Comparison

Verapamil or hypocalcemic blood perfusate during… vs Absence of verapamil or normal [Ca2+]o

Design

Preclinical

Authors

WCWayne E. CascioElectrophysiology GYGan‐Xin YanElectrophysiology AKAndré G. KléberElectrophysiology

Discussion

Member takes

Implication

No immediate clinical implications; leaves open translation of delayed uncoupling beyond rabbit models.

Key Points

This research examines how passive electrical properties and extracellular potassium levels affect mechanical activity in rabbit ventricular muscle during ischemia.
Isolated rabbit papillary muscle was examined under arterial perfusion and ischemia.
Verapamil and reduced extracellular calcium concentrations were administered to observe their effects on electrical properties and mechanical activity.
Measurements included longitudinal conduction velocity, extracellular potassium concentration, and isometric twitch tension.
Verapamil reduced maximal isometric twitch tension by 48% and hypocalcemia by 78%.
Conduction velocity decreased from 54 to 36 cm/sec after 12 minutes of ischemia in the absence of verapamil.
Electrical cell-to-cell uncoupling was completed within 15 minutes of ischemia, correlated with an increase in extracellular potassium.

Structured PICO

Does verapamil or hypocalcemia alter passive electrical properties, mechanical activity, and extracellular potassium in arterially perfused and ischemic rabbit ventricular muscle?

Population

Isolated rabbit papillary muscle

Intervention

Verapamil (0.5 microM) or hypocalcemic blood perfusate (free [Ca2+]o = 0.4 mM) during normal arterial perfusion and no-flow ischemia

Comparator

Absence of verapamil or normal [Ca2+]o

Outcome

Passive electrical resistive properties, longitudinal conduction velocity, extracellular potassium concentration, and mechanical activitysurrogate

Verapamil delays the onset of electrical uncoupling, extracellular potassium accumulation, and ischemic contracture in ischemic rabbit ventricular muscle.

Cite This Study

Cascio et al. (1990) studied this question.

synapsesocial.com/papers/6a1c8d14ecffbcc5fca17d50 https://doi.org/10.1161/01.res.66.6.1461

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June 1, 1990Circulation Research

Passive electrical properties, mechanical activity, and extracellular potassium in arterially perfused and ischemic rabbit ventricular muscle. Effects of calcium entry blockade or hypocalcemia.

View Full Paper

Ask AI

Bookmark

Why the study?

Does verapamil or hypocalcemia alter passive electrical properties, mechanical activity, and extracellular potassium in arterially perfused and ischemic rabbit ventricular muscle?

Population

Isolated rabbit papillary muscle

Comparison

Verapamil or hypocalcemic blood perfusate during… vs Absence of verapamil or normal [Ca2+]o

Design

Preclinical

Authors

WCWayne E. CascioElectrophysiology GYGan‐Xin YanElectrophysiology AKAndré G. KléberElectrophysiology

Discussion

Member takes

Implication

No immediate clinical implications; leaves open translation of delayed uncoupling beyond rabbit models.

Key Points

This research examines how passive electrical properties and extracellular potassium levels affect mechanical activity in rabbit ventricular muscle during ischemia.
Isolated rabbit papillary muscle was examined under arterial perfusion and ischemia.
Verapamil and reduced extracellular calcium concentrations were administered to observe their effects on electrical properties and mechanical activity.
Measurements included longitudinal conduction velocity, extracellular potassium concentration, and isometric twitch tension.
Verapamil reduced maximal isometric twitch tension by 48% and hypocalcemia by 78%.
Conduction velocity decreased from 54 to 36 cm/sec after 12 minutes of ischemia in the absence of verapamil.
Electrical cell-to-cell uncoupling was completed within 15 minutes of ischemia, correlated with an increase in extracellular potassium.

Structured PICO

Does verapamil or hypocalcemia alter passive electrical properties, mechanical activity, and extracellular potassium in arterially perfused and ischemic rabbit ventricular muscle?

Population

Isolated rabbit papillary muscle

Intervention

Verapamil (0.5 microM) or hypocalcemic blood perfusate (free [Ca2+]o = 0.4 mM) during normal arterial perfusion and no-flow ischemia

Comparator

Absence of verapamil or normal [Ca2+]o

Outcome

Passive electrical resistive properties, longitudinal conduction velocity, extracellular potassium concentration, and mechanical activitysurrogate

Verapamil delays the onset of electrical uncoupling, extracellular potassium accumulation, and ischemic contracture in ischemic rabbit ventricular muscle.

Cite This Study

Cascio et al. (1990) studied this question.

synapsesocial.com/papers/6a1c8d14ecffbcc5fca17d50 https://doi.org/10.1161/01.res.66.6.1461

Also Consider

Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context:

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