What question did this study set out to answer?

To determine how sarcoplasmic reticulum calcium concentration influences calcium spark generation and spontaneous transient outward currents in single smooth muscle cells.

February 1, 1999The Journal of General PhysiologyOpen Access

The Influence of Sarcoplasmic Reticulum Ca2+ Concentration on Ca2+ Sparks and Spontaneous Transient Outward Currents in Single Smooth Muscle Cells

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Population

Single patch-clamped smooth muscle cells freshly dissociated from toad stomach

Comparison

Removal of extracellular Ca2+ and brief pulse of… vs Resting state

Design

Preclinical

Authors

RZRonghua ZhuGeUMass Memorial Health Care RTRichard A. TuftWorcester Polytechnic Institute KFKevin E. FogartyAlbert Einstein College of Medicine

Discussion

Member takes

Implication

Suggests a tight spatial coupling between calcium release sites and potassium channels in smooth muscle; leaves open.

Key Points

To determine how sarcoplasmic reticulum calcium concentration influences calcium spark generation and spontaneous transient outward currents in single smooth muscle cells.
Isolated single smooth muscle cells from toad stomach and applied patch-clamp electrophysiology alongside high-speed wide-field imaging.
Concurrently monitored sarcoplasmic reticulum calcium ([Ca2+]SR), global cytosolic calcium ([Ca2+]CYTO), and spontaneous transient outward currents (STOCs) under varying holding potentials, extracellular calcium deprivation, and caffeine (20 mM) application.
Ca2+ spark onset coincided with the upstroke of STOCs, increasing local [Ca2+]CYTO by ~100 nM above a 100 nM baseline, with spark frequency and amplitude persisting unchanged for 10 min in extracellular Ca2+-free solution (50 µM EGTA).
Following caffeine depletion, STOC frequency remained suppressed until [Ca2+]SR recovered to ≥60% of baseline and rose steeply above 80%, whereas STOC amplitude scaled linearly with [Ca2+]SR.

Structured PICO

Population

Single patch-clamped smooth muscle cells freshly dissociated from toad stomach

Intervention

Removal of extracellular Ca2+ (nominally Ca2+-free solution with 50 microM EGTA) and brief pulse of caffeine (20 mM)

Comparator

Resting state

Outcome

Relationship between sarcoplasmic reticulum Ca2+ concentration ([Ca2+]SR), Ca2+ sparks, and spontaneous transient outward currents (STOCs)surrogate

The regulation of sarcoplasmic reticulum Ca2+ concentration governs Ca2+ sparks and spontaneous transient outward currents in smooth muscle cells, implying a close association between Ca2+ release sites and Ca2+-activated potassium channels.

Cite This Study

ZhuGe et al. (1999) studied this question.

synapsesocial.com/papers/69fd7e27eaf018ad124ba06a https://doi.org/10.1085/jgp.113.2.215

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The Influence of Sarcoplasmic Reticulum Ca2+ Concentration on Ca2+ Sparks and Spontaneous Transient Outward Currents in Single Smooth Muscle Cells

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

The Influence of Sarcoplasmic Reticulum Ca2+ Concentration on Ca2+ Sparks and Spontaneous Transient Outward Currents in Single Smooth Muscle Cells

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

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