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October 1, 1997Circulation Research

The effects of systolic Ca2+ on the L-type Ca2+ current and Na+-Ca2+ exchange current regulate sarcoplasmic reticulum Ca2+ content and the systolic Ca2+ transient in ventricular myocytes.

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Population

Ferret and rat ventricular myocytes

Design

Preclinical

Key result

The effects of systolic Ca2+ on the L-type Ca2+ current and Na+-Ca2+ exchange current regulate sarcoplasmic reticulum Ca2+ content and the systolic Ca2+ transient in ventricular myocytes.

Authors

ATAndrew W. TraffordMDM.E. DíazNNNicholas M. Negretti

Discussion

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Overview

Supports Ca2+ feedback in animal myocytes; hypothesis-generating and leaves open human translation.

Key Points

  • To elucidate the mechanisms by which calcium influx and efflux restore sarcoplasmic reticulum calcium content following depletion in ventricular myocytes.
  • Measured intracellular calcium transients using the fluorescent indicator indo-1 in voltage-clamped rat and ferret ventricular myocytes.
  • Estimated sarcoplasmic reticulum calcium content by integrating caffeine-evoked sodium-calcium exchange currents across repetitive electrical stimulation pulses.
  • Early recovery pulses exhibited greater calcium influx via L-type calcium currents than calcium extrusion via the sodium-calcium exchanger until reaching equal flux at steady state.
  • The cumulative net cellular calcium gain matched the total replenishment of sarcoplasmic reticulum calcium content estimated from caffeine-induced currents.
  • A nonlinear relationship was identified where increments in sarcoplasmic reticulum calcium at high levels produced disproportionately larger systolic calcium transients than at low levels.

Structured PICO

P
Population
Ferret and rat ventricular myocytes
I
Intervention
Voltage-clamp stimulation and caffeine application
O
Outcome
Sarcoplasmic reticulum (SR) Ca2+ content and systolic Ca2+ transientsurrogate

The study demonstrates that the effects of systolic Ca2+ on Ca2+ current and Na+-Ca2+ exchange current regulate SR Ca2+ content and the systolic Ca2+ transient in ventricular myocytes.

Cite This Study

Trafford et al. (1997) studied this question. Electrical stimulation and caffeine application was evaluated on Sarcoplasmic reticulum Ca2+ content and systolic Ca2+ transient. The effects of systolic Ca2+ on the L-type Ca2+ current and Na+-Ca2+ exchange current regulate sarcoplasmic reticulum Ca2+ content and the systolic Ca2+ transient in ventricular myocytes.

synapsesocial.com/papers/6a172d44add869d0012c2602https://doi.org/10.1161/01.res.81.4.477
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