Key Points
- To characterize gating currents associated with sodium channels in canine cardiac Purkinje cells.
- Recorded gating currents in single canine cardiac Purkinje cells at temperatures of 10-12 degrees C.
- Analyzed charge density and charge-voltage relationships related to peak sodium conductance.
- Fitted macroscopic currents to Hodgkin-Huxley models for activation analysis.
- Charge density predicted by peak INa was 0.14-0.22 fC micron -2 and measured at 0.19 +/- 0.10 fC micron -2 (n=28).
- The charge-voltage relationship exhibited similar midpoints but a steeper conductance curve of 1.5 +/- 0.3 (n=9).
- Gating current relaxations better fitted two exponentials, indicating complex dynamics at various voltages.
Structured PICO
PPopulationSingle canine cardiac Purkinje cells (n=28 for charge density measurement)
IInterventionElectrophysiological recording of gating currents (Ig) at 10-12 degrees C
OOutcomeGating current characteristics and their relationship to macroscopic INa characteristicssurrogate
Single canine cardiac Purkinje cells are a suitable model for combining gating current and single-channel measurements to obtain a kinetic description of the cardiac Na channel.