Key result
Driving ventricular Purkinje fibers at a rate higher than their intrinsic rate activates an electrogenic Na+ pump, which is the major mechanism responsible for overdrive suppression.
Why the study?
Does driving ventricular Purkinje fibers at a fast rate cause overdrive suppression via the activation of an electrogenic Na+ pump?
Population
Sheep and dog Purkinje fibers perfused in vitro
Comparison
Driving Purkinje fibers at a fast rate for… vs Control (baseline intrinsic rate)
Design
Preclinical
Authors
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In vitro Purkinje data warrant no practice change; leaves open in vivo confirmation of overdrive mechanisms.
Does driving ventricular Purkinje fibers at a fast rate cause overdrive suppression via the activation of an electrogenic Na+ pump?
Overdrive suppression of automaticity in Purkinje fibers is primarily mediated by the activation of an electrogenic Na+ pump following an initial loss of K+.
Mario Vassalle (1970) studied this question. Driving Purkinje fibers at a fast rate (overdrive) vs. Control (intrinsic rate) was evaluated on Mechanism of overdrive suppression (membrane potential, slope of diastolic depolarization, threshold voltage). Driving ventricular Purkinje fibers at a rate higher than their intrinsic rate activates an electrogenic Na+ pump, which is the major mechanism responsible for overdrive suppression.
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