What is the clinical evidence from this study?

Study design: Other. Intervention: Voltage clamp. Primary outcome: Membrane current and extracellular K accumulation.

What question did this study set out to answer?

To characterize individual membrane potassium currents in frog ventricular muscle and determine their direct relationship to extracellular potassium accumulation.

January 1, 1979The Journal of PhysiologyOpen Access

Potassium currents in frog ventricular muscle: evidence from voltage clamp currents and extracellular K accumulation.

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Key result

In frog ventricular muscle, slow current changes are related to K current across the membrane, which can be separated into an inwardly-rectifying K current and a time-dependent K current.

Population

Strips of frog ventricular muscle

Design

Preclinical

Authors

LCLars Nilausen CleemannMoesgaard Museum MMMartin MoradElectrophysiology

Discussion

Member takes

Implication

Offers no immediate clinical guidance; leaves open applicability of frog K current separation to mammalian myocardium.

Key Points

To characterize individual membrane potassium currents in frog ventricular muscle and determine their direct relationship to extracellular potassium accumulation.
Applied the single sucrose gap voltage clamp technique to isolated strips of frog ventricular muscle to control membrane potential and measure total membrane current.
Estimated extracellular potassium accumulation by measuring the after-potentials generated immediately following the release of the voltage clamp.
Evaluated current-voltage relationships, temperature sensitivity (Q10), and the pharmacological blocking effect of cesium.
Identified an inwardly rectifying potassium current dominating below -20 mV that causes rapid after-potentials, has a maximum of ~2 µA/cm², exhibits negative slope conductance increased by extracellular potassium, has a Q10 of ~1.35, and is blocked by cesium.
Characterized a second potassium current dominating positive to -20 mV that is time- and potential-dependent, develops after-potentials with delay, has a Q10 of 3–4, and is insensitive to cesium.
Separated total membrane current into an accumulation-related potassium current and a residual linear or slightly rectifying current that reaches ~1 µA/cm² at -20 mV.

Structured PICO

Population

Strips of frog ventricular muscle

Intervention

Single sucrose voltage clamp technique, alterations in extracellular K concentration, and addition of Cs

Outcome

Membrane current and extracellular K accumulation (estimated from after-potential)surrogate

This basic science study characterizes the distinct inwardly rectifying and time-dependent potassium currents in frog ventricular muscle and their differential relationship to extracellular potassium accumulation.

Cite This Study

Cleemann et al. (1979) studied this question. Voltage clamp was evaluated on Membrane current and extracellular K accumulation. In frog ventricular muscle, slow current changes are related to K current across the membrane, which can be separated into an inwardly-rectifying K current and a time-dependent K current.

synapsesocial.com/papers/6a0a1d514b13cba79251956a https://doi.org/10.1113/jphysiol.1979.sp012609

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January 1, 1979The Journal of PhysiologyOpen Access

Potassium currents in frog ventricular muscle: evidence from voltage clamp currents and extracellular K accumulation.

View Full Paper

Ask AI

Bookmark

Key result

In frog ventricular muscle, slow current changes are related to K current across the membrane, which can be separated into an inwardly-rectifying K current and a time-dependent K current.

Population

Strips of frog ventricular muscle

Design

Preclinical

Authors

LCLars Nilausen CleemannMoesgaard Museum MMMartin MoradElectrophysiology

Discussion

Member takes

Implication

Offers no immediate clinical guidance; leaves open applicability of frog K current separation to mammalian myocardium.

Key Points

To characterize individual membrane potassium currents in frog ventricular muscle and determine their direct relationship to extracellular potassium accumulation.
Applied the single sucrose gap voltage clamp technique to isolated strips of frog ventricular muscle to control membrane potential and measure total membrane current.
Estimated extracellular potassium accumulation by measuring the after-potentials generated immediately following the release of the voltage clamp.
Evaluated current-voltage relationships, temperature sensitivity (Q10), and the pharmacological blocking effect of cesium.
Identified an inwardly rectifying potassium current dominating below -20 mV that causes rapid after-potentials, has a maximum of ~2 µA/cm², exhibits negative slope conductance increased by extracellular potassium, has a Q10 of ~1.35, and is blocked by cesium.
Characterized a second potassium current dominating positive to -20 mV that is time- and potential-dependent, develops after-potentials with delay, has a Q10 of 3–4, and is insensitive to cesium.
Separated total membrane current into an accumulation-related potassium current and a residual linear or slightly rectifying current that reaches ~1 µA/cm² at -20 mV.

Structured PICO

Population

Strips of frog ventricular muscle

Intervention

Single sucrose voltage clamp technique, alterations in extracellular K concentration, and addition of Cs

Outcome

Membrane current and extracellular K accumulation (estimated from after-potential)surrogate

Cite This Study

synapsesocial.com/papers/6a0a1d514b13cba79251956a https://doi.org/10.1113/jphysiol.1979.sp012609

Also Consider

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

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