April 1, 1995Journal of Cardiovascular Electrophysiology
Responses of the Transmembrane Potential of Myocardial Cells during a Shocks
Key result
Extracellular electrical field stimulation during the action potential plateau caused nonlinear transmembrane potential changes, with hyperpolarization magnitude 1.9 times that of depolarization (P<0.05).
Population
Seven guinea pig papillary muscles
Comparison
Extracellular electrical field stimulation… vs Different shock strengths and polarities
Design
Preclinical
Authors
Discussion
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Member takes
Overview
Does not inform clinical stimulation protocols; leaves open translation of nonlinear field effects to arrhythmia therapies.
Key Points
- This investigation aims to study the changes in transmembrane potential during electrical stimulation in myocardial cells.
- Recorded transmembrane potential (Vm) in guinea pig papillary muscles using a double-barrel microelectrode
- Delivered electrical shocks of varying strengths during the action potential plateau and diastole
- Analyzed the membrane responses to both depolarizing and hyperpolarizing shocks.
- Peak delta Vm increased with potential gradients, with significant differences noted (P < 0.05)
- Magnitude of hyperpolarization was approximately 1.9 times that of depolarization (P < 0.05)
- Time constant of membrane response decreased significantly as potential gradients increased (P < 0.01).
Structured PICO
P
Population
7 guinea pig papillary muscles studied in a tissue bath to evaluate transmembrane potential changes during extracellular electrical field stimulation.
I
Intervention
Extracellular electrical field stimulation (10-msec square wave shocks creating field strengths of 1.7, 2.9, 6.1, and 8.8 V/cm) delivered during action potential plateau or diastole
C
Comparator
Different shock strengths and polarities
O
Outcome
Transmembrane potential changes (delta Vm)surrogate
During the action potential plateau, the myocardial membrane response to electrical shocks is non-linear and cannot be represented by a classic passive RC membrane model.
Cite This Study
Zhou et al. (1995) studied this question. Extracellular electrical field stimulation (shocks) vs. Different shock strengths and polarities was evaluated on Transmembrane potential changes (delta Vm). Extracellular electrical field stimulation during the action potential plateau caused nonlinear transmembrane potential changes, with hyperpolarization magnitude 1.9 times that of depolarization (P<0.05).