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Interstitial potential during propagation in bathed ventricular muscle.
S B Knisley1, T Maruyama, J W Buchanan
1Division of Cardiology, University of North Carolina, Chapel Hill.
Biophysical Journal
|March 1, 1991
Summary
Interstitial potential (Vis) significantly impacts transmembrane action potential measurements in ventricular muscle. This study experimentally quantifies Vis effects, revealing underestimations in depolarization and overestimations in action potential foot measurements.
Area of Science:
- Cardiac Electrophysiology
- Biophysics
- Computational Biology
Background:
- Theoretical models suggest interstitial potential (Vis) influences transmembrane action potential (TM) recordings.
- Experimental validation of Vis effects on action potential propagation in ventricular muscle is needed.
Purpose of the Study:
- To experimentally evaluate the impact of interstitial potential (Vis) on transmembrane action potential (TM) measurements.
- To quantify the discrepancies introduced by Vis in action potential propagation parameters.
Main Methods:
- Recorded Vis and intracellular action potential (Vic) at various depths in paced guinea pig papillary muscles.
- Calculated TM by subtracting Vic from Vis recordings.
- Compared TM measurements with Vic recordings to assess Vis influence.
Main Results:
- Vis amplitude and dV/dtmax varied with depth, peaking at 200 microns.
- Vic underestimated TM's phase zero depolarization (dV/dtmax) by 20-31%.
- Vic overestimated the action potential foot time constant by 48-82%, affecting capacitance estimates.
Conclusions:
- Interstitial potential significantly distorts quantitative measurements of the ventricular action potential.
- Vis effects can lead to inaccurate estimations of ionic currents and membrane properties.
- These findings highlight the importance of accounting for Vis in electrophysiological studies.