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December 1, 1996AJP Heart and Circulatory Physiology

Transmembrane potential changes caused by shocks in guinea pig papillary muscle

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Population

10 guinea pig papillary muscles

Comparison

10-ms extracellular field stimulation shocks at… vs Baseline responses before TTX/Ca-free perfusion…

Design

Preclinical

Key result

Extracellular field stimulation caused non-linear transmembrane potential changes and induced action potentials even when Na+ channels were inactivated by TTX.

Authors

XZXiaoya ZhouWSW.M. SmithDRDennis L. Rollins

Discussion

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Overview

Hypothesis-generating for non-Na+ pathways in field-induced cardiac excitation; should not yet change defibrillation practice.

Structured PICO

P
Population
10 guinea pig papillary muscles studied to evaluate transmembrane potential changes caused by extracellular field stimulation.
I
Intervention
10-ms extracellular field stimulation shocks at six strengths (1.8 to 17.8 V/cm) with both polarities, delivered during action potential plateau or diastole, followed by perfusion with 30 microM tetrodotoxin (TTX) (n=5) or TTX plus Ca(2+)-free solution (n=5)
C
Comparator
Baseline responses before TTX/Ca(2+)-free perfusion, and point stimuli (10 times diastolic threshold)
O
Outcome
Transmembrane potential (Vm) changes (delta Vm) caused by extracellular field stimulationsurrogate

This preclinical study demonstrates that the relationship between transmembrane potential changes and shock potential gradient is nonlinear, and field stimulation can induce action potentials even when Na+ channels are inactivated.

Cite This Study

Zhou et al. (1996) studied this question. Extracellular field stimulation (10-ms shock) vs. Before/after TTX or TTX plus Ca2+-free perfusion was evaluated on Transmembrane potential changes (delta Vm). Extracellular field stimulation caused non-linear transmembrane potential changes and induced action potentials even when Na+ channels were inactivated by TTX.

synapsesocial.com/papers/6a9404d601d6912b871d4e70https://doi.org/10.1152/ajpheart.1996.271.6.h2536
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