What question did this study set out to answer?

To characterize the macroscopic potassium currents and their regulatory mechanisms in single smooth muscle cells isolated from rabbit portal veins.

June 1, 1989The Journal of PhysiologyOpen Access

Macroscopic K+ currents in single smooth muscle cells of the rabbit portal vein.

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Population

Single smooth muscle cells isolated from rabbit portal vein

Comparison

Voltage clamp using whole-cell patch-clamp… vs Control conditions

Design

Preclinical

Authors

JHJoseph R. HumeElectrophysiology NLNormand LeblancUniversity of Nevada, Reno

Discussion

Member takes

Implication

Extends vascular K+ current characterization in animal models; leaves open translation to human vascular physiology or therapy.

Key Points

To characterize the macroscopic potassium currents and their regulatory mechanisms in single smooth muscle cells isolated from rabbit portal veins.
Isolated single smooth muscle cells from rabbit portal vein and recorded electrical activity using whole-cell patch-clamp electrophysiology at room temperature.
Manipulated intracellular and extracellular ion compositions—including calcium removal, barium substitution, and internal caesium/TEA dialysis—alongside varied micropipette tip diameters to evaluate dialyzed versus non-dialyzed conditions.
Depolarization revealed four distinct outward currents: a quasi-instantaneous background current, a non-inactivating delayed rectifier current, a smooth transient outward current (Ito), and spontaneous transient outward currents (STOCs).
Removal of external calcium or dialyzing with high internal EGTA (5 mM) completely abolished both Ito and STOCs while sparing the delayed rectifier, confirming calcium-dependent activation of transient currents.
External tetraethylammonium (0.5–20 mM) blocked all four outward currents, whereas intracellular replacement of potassium with caesium and TEA eliminated all outward currents and unmasked a small inward calcium current in ~60% of dialyzed cells.

Structured PICO

Population

Single smooth muscle cells isolated from rabbit portal vein

Intervention

Voltage clamp using whole-cell patch-clamp technique with various internal and external solutions (EGTA, ATP, TEA, barium, caesium, caffeine)

Comparator

Control conditions (undialyzed cells, normal calcium bathing solution)

Outcome

Characterization of macroscopic K+ currents (background, delayed rectifier, Ito, STOCs)surrogate

This preclinical study characterizes four distinct macroscopic potassium currents in rabbit portal vein smooth muscle cells, highlighting the calcium-dependence of transient outward currents.

Cite This Study

Hume et al. (1989) studied this question.

synapsesocial.com/papers/6a71b3185d37378ac1dec6ad https://doi.org/10.1113/jphysiol.1989.sp017641

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Macroscopic K+ currents in single smooth muscle cells of the rabbit portal vein.

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Macroscopic K+ currents in single smooth muscle cells of the rabbit portal vein.

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

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