What question did this study set out to answer?

To investigate the effects of varying intracellular magnesium concentrations, particularly depletion, on the delayed rectifier potassium current in cardiac ventricular myocytes.

January 1, 1998The Japanese Journal of Physiology

Intracellular Mg2+ Depletion Depresses the Delayed Rectifier K+ Current in Guinea Pig Ventricular Myocytes.

View Full Paper

Ask AI

Bookmark

Population

Guinea pig ventricular myocytes

Comparison

Various intracellular magnesium concentrations… vs Internal solutions with 0.03 to 1 mM [Mg2+]i and…

Design

Preclinical

Follow-up

10 min

Authors

KHKenji HiraharaJapan Atomic Energy Agency TMTaro MatsubayashiSaga Medical School Hospital HMHiroshi MatsuuraShiga University of Medical Science

Discussion

Member takes

Implication

Low intracellular Mg2+ impairs IK maintenance in ventricular myocytes; leaves open relevance to human electrophysiology or arrhythmias.

Key Points

To investigate the effects of varying intracellular magnesium concentrations, particularly depletion, on the delayed rectifier potassium current in cardiac ventricular myocytes.
Measured delayed rectifier potassium currents in isolated guinea pig ventricular myocytes using whole-cell patch-clamp and pipette-perfusion techniques.
Quantified current amplitude from repolarization tail currents across internal magnesium concentrations ranging from below 0.01 mM to 3 mM.
Evaluated channel phosphorylation dependence using ATP-γ-S loading, isoprenaline stimulation, and okadaic acid exposure.
Perfusion with intracellular magnesium below 0.01 mM caused current to transiently increase and then progressively decline to approximately 30% of its initial magnitude within 10 minutes.
Currents remained relatively stable at 0.03 to 1 mM intracellular magnesium, whereas exposure to 3 mM elicited a rapid current decline.
The magnesium-depletion current decline occurred without significant changes in voltage activation or deactivation kinetics and persisted in the presence of okadaic acid and ATP-γ-S loading.

Structured PICO

Population

Guinea pig ventricular myocytes

Intervention

Various intracellular magnesium concentrations ([Mg2+]i), particularly low [Mg2+]i (<0.01 mM)

Comparator

Internal solutions with 0.03 to 1 mM [Mg2+]i and 3 mM [Mg2+]i

Outcome

Magnitude of the delayed rectifier K+ current (IK)surrogate

Intracellular Mg2+ concentrations higher than 0.01 mM are required to maintain the delayed rectifier K+ current in guinea pig ventricular cells via a phosphorylation-independent mechanism.

Cite This Study

Hirahara et al. (1998) studied this question.

synapsesocial.com/papers/6a715589f44fa9f079df21cf https://doi.org/10.2170/jjphysiol.48.81

View Full Paper

Ask AI

Bookmark

Intracellular Mg2+ Depletion Depresses the Delayed Rectifier K+ Current in Guinea Pig Ventricular Myocytes.

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Intracellular Mg2+ Depletion Depresses the Delayed Rectifier K+ Current in Guinea Pig Ventricular Myocytes.

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Also Consider

Also Consider