What does this research mean for the field?

Intracellular chloride activity in mammalian heart muscle is maintained at levels three to four times higher than expected from passive electrochemical distribution, suggesting the presence of an active inwardly directed chloride pump. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

To determine whether intracellular chloride ions are passively distributed or actively maintained across cardiac cell membranes using ion-sensitive micro-electrodes.

October 1, 1979The Journal of PhysiologyOpen Access

Non‐passive chloride distribution in mammalian heart muscle: micro‐electrode measurement of the intracellular chloride activity.

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Population

Quiescent sheep cardiac Purkinje fibres and guinea-pig papillary muscle in vitro

Design

Preclinical

Authors

RVRichard D. Vaughan‐JonesElectrophysiology

Discussion

Member takes

Implication

Challenges passive Cl distribution in cardiac muscle; leaves open active inward pump for further study.

Key Points

To determine whether intracellular chloride ions are passively distributed or actively maintained across cardiac cell membranes using ion-sensitive micro-electrodes.
Measured intracellular chloride activity continuously in quiescent sheep cardiac Purkinje fibres and guinea-pig papillary muscle in vitro using liquid ion-exchanger micro-electrodes.
Assessed chloride distribution kinetics during exposure to chloride-free solutions, varying extracellular calcium concentrations (0 to 12 mM), and high-potassium depolarizing solutions (45 mM).
Resting intracellular chloride activity was 3 to 4 times higher than predicted by passive distribution (~5 mM), resulting in a chloride equilibrium potential roughly 35 mV positive to membrane potential.
Intracellular chloride activity was more than twice as high in bicarbonate-free HEPES buffer, while high-potassium depolarization (45 mM) shifted chloride to passive distribution where membrane potential and chloride equilibrium potential differed by less than 2 mV.

Structured PICO

Population

Quiescent sheep cardiac Purkinje fibres and guinea-pig papillary muscle in vitro

Intervention

Measurement of intracellular Cl activity using liquid ion-exchanger Cl- -sensitive micro-electrodes under various conditions (e.g., absence of bicarbonate/CO2, Cl-free solutions, high-K solutions)

Outcome

Intracellular chloride activity (aCli) and equilibrium potential (ECl) relative to membrane potential (Em)surrogate

Intracellular chloride in mammalian cardiac muscle is not passively distributed, suggesting the possible existence of an inwardly directed chloride pump.

Cite This Study

Richard D. Vaughan‐Jones (1979) studied this question.

synapsesocial.com/papers/6a1bf8811567d2fc4d5f593d https://doi.org/10.1113/jphysiol.1979.sp012956

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Non‐passive chloride distribution in mammalian heart muscle: micro‐electrode measurement of the intracellular chloride activity.

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Non‐passive chloride distribution in mammalian heart muscle: micro‐electrode measurement of the intracellular chloride activity.

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

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