Key Points
- To explore the effects of Cs(+), K(+), and Rb(+) on the pace-maker current in calf Purkinje fibers.
- Investigated I-V relations with varying concentrations of Cs(+), K(+), and Rb(+).
- Analyzed the blockade effects and current changes across different membrane potentials.
- Modeled current responses with Michaelis-Menten kinetics for K(+)-induced activation.
- Cs(+) induces blockade in negative voltage ranges and increases current at positive potentials, K(+) shows similar cross-over behavior.
- Dissociation constants for Cs(+) ranged from 0.5-3.7 mM, while for Rb(+) they ranged from 1.4-5.4 mM under varying ionic conditions.
- The current increase from Cs(+) is large in low-K(+) environments and diminishing in high-K(+), indicating competition between ions.
Structured PICO
PPopulationCalf Purkinje fibres
IInterventionCaesium (Cs+) 0.01-3mM, Potassium (K+), and Rubidium (Rb+)
OOutcomeEffects on the fully activated I-V relation ī(f)(E) for the pace-maker currentsurrogate
The study characterizes the i_f pace-maker channel in calf Purkinje fibres, identifying distinct inner blocking and external activatory sites for monovalent cations.