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Modeling action potential reversals in tunicate hearts
John W Cain1, Luran He1, Lindsay Waldrop2
1Department of Mathematics, Harvard University, Cambridge, Massachusetts 02138, USA.
Physical Review. E
|January 20, 2021
Summary
Tunicates exhibit unique heart flow reversals. This study models action potential propagation to uncover the electrophysiological basis and conditions triggering these reversals, offering insights into cardiac function.
Area of Science:
- Cardiovascular Physiology
- Computational Biology
- Invertebrate Zoology
Background:
- Tunicates possess a unique heart that can reverse blood flow direction.
- The underlying electrophysiological mechanisms driving these flow reversals remain debated.
- Understanding these mechanisms could provide insights into cardiac function in other species.
Purpose of the Study:
- To investigate the electrophysiological basis of flow reversals in the tunicate heart.
- To develop a computational model simulating action potential propagation.
- To identify conditions that trigger retrograde propagation.
Main Methods:
- Developed an idealized model of the tubelike tunicate heart.
- Utilized asymptotic formulas for action potential duration and conduction velocity.
- Employed a two-current ionic model and a kinematic model for analysis.
- Performed numerical simulations of action potential propagation.
Main Results:
- Derived analytical criteria for the occurrence of flow reversals.
- Identified the role of pacemaker firing rate variability in generating reversals.
- Determined favorable conditions for triggering retrograde propagation.
- Simulations confirmed the model's ability to reproduce reversals.
Conclusions:
- The study provides an electrophysiological explanation for tunicate heart flow reversals.
- The analytical framework is applicable to modeling cardiac function in other species, including humans.
- Variability in pacemaker activity is a key factor in initiating retrograde propagation.
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