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Factors governing mechanical stimulation in frog hearts
1Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
The American Journal of Physiology
|December 22, 1999
Summary
Mechanical stretch can activate heart tissue, similar to electrical stimuli. Increasing stretch speed or baseline stretch lowers the threshold for this mechanical activation, offering insights into cardiac arrhythmias.
Area of Science:
- Cardiology
- Biophysics
- Mechanobiology
Background:
- Stretch-induced activation is implicated in cardiac arrhythmias.
- Understanding mechanical activation is crucial for cardiac electrophysiology.
Purpose of the Study:
- To investigate how different types of mechanical stretch activate ventricular tissue.
- To determine the effects of stretch parameters on the mechanical activation threshold.
Main Methods:
- Ventricular tissue from frog hearts (Rana catesbeiana) was used.
- Stretches were applied perpendicular to tissue edges.
- Varied stretch speed and baseline stretch to assess activation thresholds.
Main Results:
- All tested tissue samples were activated by stretch pulses.
- Higher stretch was required at shorter coupling intervals, mirroring electrical strength-interval relations.
- Increased stretch speed and baseline stretch decreased the mechanical activation threshold.
Conclusions:
- Mechanical activation of cardiac tissue shares similarities with electrical activation.
- Stretch speed and baseline stretch are key mechanical parameters influencing activation threshold.
- Findings provide a basis for understanding stretch-induced arrhythmias.