Synapse
⌘+K
Synapse
PulseExploreClubsResearchersJournals
Instagram
HomeClubsExplore
July 1, 1978The Journal of PhysiologyOpen Access

Potassium efflux in heart muscle during activity: extracellular accumulation and its implications.

View Full Paper
Ask AI
Bookmark
Share

Population

Frog ventricular muscle

Design

Preclinical

Authors

RKRichard KlineCalgary Laboratory ServicesMMMartin MoradElectrophysiology

Discussion

Loading...

Member takes

Implication

K+ efflux during frog ventricular action potentials may influence local electrophysiology; leaves open relevance to mammalian arrhythmia mechanisms.

Key Points

  • To quantify extracellular potassium accumulation during cardiac electrical activity and determine its impact on membrane potential and action potential dynamics.
  • Simultaneously monitored extracellular K+ activity and transmembrane potential in frog ventricular muscle using K+-selective and standard intracellular microelectrodes.
  • Employed double-barrelled K+ microelectrodes with rapid electrical compensation to measure real-time K+ changes during single action potentials.
  • Assessed K+ accumulation and clearance kinetics across variations in stimulation frequency, muscle diameter, bath temperature, external K+ concentration, and nickel exposure.
  • Potassium accumulated continuously during the action potential plateau, raising extracellular concentration by approximately 1 mM and generating a net efflux of 10 to 30 pmole/cm2·s (1 to 3 µA/cm2).
  • Accumulation magnitude depended on stimulation rate, muscle diameter, and temperature, with clearance kinetics exhibiting a Q10 of 2.
  • Elevating external K+ shortened action potential duration and depolarized membranes without altering accumulation rate, whereas nickel ions prolonged action potentials while reducing K+ accumulation rates.

Structured PICO

P
Population
Frog ventricular muscle
I
Intervention
Electrical stimulation at varying frequencies, temperatures, and external K+ concentrations, and in the presence of Ni2+
O
Outcome
Extracellular K+ activity and transmembrane potentialsurrogate

Substantial and continuous efflux of K+ occurs during the action potential in frog ventricular muscle, leading to extracellular accumulation that can cause membrane depolarization and alter action potential duration.

Cite This Study

Kline et al. (1978) studied this question.

synapsesocial.com/papers/6a74bace508d802509f546fahttps://doi.org/10.1113/jphysiol.1978.sp012400
View Full Paper
Ask AI
Bookmark
Share

Also Consider

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

  1. 1THE ULTRASTRUCTURE OF FROG VENTRICULAR CARDIAC MUSCLE AND ITS RELATIONSHIP TO MECHANISMS OF EXCITATION-CONTRACTION COUPLING1968 · 196 citations
  2. 2Extracellular Potassium Accumulation and Inward-Going Potassium Rectification in Voltage Clamped Ventricular Muscle1976 · 31 citations
  3. 3The efflux of potassium, sodium, chloride, calcium and sulphate ions and of sorbitol and glycerol during the cardiac cycle in frog's ventricle1968 · 15 citations
  4. 4Measurement of transmembrane potential and current in cardiac muscle: a new voltage clamp method.1977 · 42 citations
  5. 5The time and voltage dependence of the slow outward current in cardiac Purkinje fibres1966 · 198 citations