What is the clinical evidence from this study?

Study design: Other. Population: Isolated ventricular myocytes from adult guinea pig heart. Intervention: Internal magnesium ions (Mg2+) vs. Internal solution with free Mg2+ < 1 microM. Primary outcome: Rectification of the inwardly rectifying potassium channel.

What question did this study set out to answer?

Investigate the mechanism governing inward rectification in inward rectifier potassium channels of cardiac ventricular myocytes.

April 1, 1987Proceedings of the National Academy of SciencesOpen Access

Inward rectification of a potassium channel in cardiac ventricular cells depends on internal magnesium ions.

Q: What are the key findings of this study?

Inward rectification of the potassium channel in cardiac ventricular cells is due to internal block by magnesium ions, which can be eliminated by reducing internal Mg2+ to less than 1 microM.

Q: What question did this study set out to answer?

Investigate the mechanism governing inward rectification in inward rectifier potassium channels of cardiac ventricular myocytes.

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Key result

Inward rectification of the potassium channel in cardiac ventricular cells is due to internal block by magnesium ions, which can be eliminated by reducing internal Mg2+ to less than 1 microM.

Population

Isolated ventricular myocytes from adult guinea pig heart

Comparison

Alteration of internal magnesium concentration vs Different concentrations of internal Mg2+

Design

Preclinical

Authors

CVC A VandenbergKaleida Health

Discussion

Member takes

Implication

Identifies Mg2+ block of ventricular K+ channels in animal cells; leaves open relevance to human arrhythmias.

Key Points

Investigate the mechanism governing inward rectification in inward rectifier potassium channels of cardiac ventricular myocytes.
Obtained single-channel recordings using cell-attached and excised patch-clamp techniques in isolated ventricular myocytes from adult guinea pigs.
Applied voltage ramps across patches while manipulating internal calcium, external and internal potassium concentrations, and internal free magnesium concentrations (<1 µM to ~1 mM).
In cell-attached patches, single-channel potassium currents rectified strongly near the potassium equilibrium potential, with outward current completely absent at positive potentials.
Abolishing internal free magnesium to below 1 µM eliminated inward rectification in excised patches, while adding approximately 1 mM magnesium restored it fully.
Intermediate magnesium concentrations produced graded rectification accompanied by brief channel closures at potentials positive to the potassium equilibrium potential.

Structured PICO

Population

Isolated ventricular myocytes from adult guinea pig heart

Intervention

Alteration of internal magnesium (Mg2+) concentration (reduction to <1 microM, addition of ~1 mM Mg2+)

Comparator

Different concentrations of internal Mg2+

Outcome

Single-channel potassium currents and degree of rectificationsurrogate

Inward rectification of potassium channels in cardiac ventricular cells is mediated by internal block by magnesium ions.

Cite This Study

C A Vandenberg (1987) studied Isolated ventricular myocytes from adult guinea pig heart. Internal magnesium ions (Mg2+) vs. Internal solution with free Mg2+ < 1 microM was evaluated on Rectification of the inwardly rectifying potassium channel. Inward rectification of the potassium channel in cardiac ventricular cells is due to internal block by magnesium ions, which can be eliminated by reducing internal Mg2+ to less than 1 microM.

synapsesocial.com/papers/6a0fb9bb58ed9fc001fca766 https://doi.org/10.1073/pnas.84.8.2560

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Inward rectification of a potassium channel in cardiac ventricular cells depends on internal magnesium ions.

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Inward rectification of a potassium channel in cardiac ventricular cells depends on internal magnesium ions.

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

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