Key Points
- The aim is to explore the properties and roles of K+ currents in bullfrog atrial myocytes during repolarization.
- Isolated bullfrog atrial myocytes through enzymatic and mechanical dispersion.
- Used a one-microelectrode voltage clamp to record slow outward K+ currents under varied [K+]o conditions.
- Analyzed activation and deactivation kinetics through current-voltage relation studies.
- The K+ current (IK) exhibited a significant role in initiating repolarization without inactivation.
- Activation began near -50 mV, with half-activation around -16 mV; fully activated I-V curve was linear from -40 to +30 mV.
- The magnitude of IK remains consistent regardless of transmembrane Ca2+ current alterations.
Structured PICO
PPopulationIndividual myocytes isolated from bullfrog atrium
IInterventionOne-microelectrode voltage clamp recording and manipulation of extracellular K+ and Ca2+ concentrations
OOutcomeElectrophysiological properties and kinetics of the slow outward K+ current (IK)surrogate
The study characterizes the delayed rectifier K+ current in bullfrog atrial cells, demonstrating its voltage- and time-dependent properties and its role in initiating repolarization independent of calcium currents.