What question did this study set out to answer?

To determine the respective roles of sodium and calcium ion permeabilities in shaping the action potential of frog cardiac ventricular fibers using specific ion channel blockers.

September 10, 1965Science

Tetrodotoxin and Manganese Ion: Effects on Action Potential of the Frog Heart

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Population

Frog cardiac ventricle fibers and barnacle muscle fibers

Design

Preclinical

Authors

SHSusumu HagiwaraNihon University SNShigehiro NakajimaTokyo Institute of Technology

Discussion

Member takes

Implication

Distinguishes Na- and Ca-dependent phases in amphibian cardiac action potentials; leaves open translation to mammalian electrophysiology or antiarrhythmic strategies.

Key Points

To determine the respective roles of sodium and calcium ion permeabilities in shaping the action potential of frog cardiac ventricular fibers using specific ion channel blockers.
Assessed changes in action potential characteristics in frog cardiac ventricular fibers exposed to tetrodotoxin and manganese ions.
Compared cardiac responses against the calcium-dependent action potentials of barnacle muscle fibers.
Tetrodotoxin selectively suppressed the rate of rise of the ventricular action potential without affecting the overshoot, while producing no effect on barnacle muscle calcium potentials.
Manganese ions primarily suppressed the action potential overshoot in ventricular fibers and blocked barnacle muscle potentials, showing the cardiac plateau phase depends on calcium permeability.

Structured PICO

Population

Frog cardiac ventricle fibers and barnacle muscle fibers

Intervention

Tetrodotoxin and manganese ions

Outcome

Action potential characteristics (rate of rise, overshoot, plateau phase)surrogate

The study demonstrates that the plateau phase of the frog cardiac ventricle action potential is primarily related to increased membrane permeability to calcium ions.

Cite This Study

Hagiwara et al. (1965) studied this question.

synapsesocial.com/papers/6a7d5edce6f633beba6e5902 https://doi.org/10.1126/science.149.3689.1254

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Implication

Distinguishes Na- and Ca-dependent phases in amphibian cardiac action potentials; leaves open translation to mammalian electrophysiology or antiarrhythmic strategies.

Tetrodotoxin and Manganese Ion: Effects on Action Potential of the Frog Heart

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Tetrodotoxin and Manganese Ion: Effects on Action Potential of the Frog Heart

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

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