Effects of strain on cardiac electrophysiology and microstructure

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Publication Type dissertation
School or College College of Engineering
Department Bioengineering
Author McNary, Thomas Grant
Title Effects of strain on cardiac electrophysiology and microstructure
Date 2011-12
Description Does strain induce changes in the electrical properties of the heart? Does strain affect the microstructure of cardiac myocytes? Others have considered these questions, but have been limited in their findings. I addressed the first question by measuring conduction velocity in papillary muscles in rest conditions and during applied strain. I also applied streptomycin, a nonselective stretch ion channel blocker, in the above conditions. In control, conduction velocity increased with strain before conduction block occurred. When streptomycin was applied conduction velocity peaked at a higher strain, but conduction block remained unchanged. Changes in electrical properties of papillary muscle allowed for changes in conduction velocity. Although streptomycin did not alter the strain at which conduction block occurred, it did shift the peak conduction velocity to a higher strain. The second question was addressed by imaging isolated cardiac ventricular myocytes in varying degrees of contraction and strain using confocal microscopy. The length of transverse tubules (t-tubules), along with cross-section ellipticity, and orientation in myocytes were analyzed for cells in 16% contraction, rest, and 16% strain. Cells in contraction showed an increase in length of t-tubules with less elliptical cross-sections compared to cells in rest. Strained cells showed a decrease in length of t-tubules with less elliptical cross-sections than cells at rest. The orientation of t-tubule cross-sections changed in a similar manner when comparing contracted and strained cells with cells at rest. The transfer of strain to the t-tubule system supports the hypothesis that the motion of t-tubules during contraction and stretch may constitute a mechanism for pumping extracellular fluid.
Type Text
Publisher University of Utah
Subject Capacitance; Conduction velocity; Heart; Stretch; Transverse tubule
Dissertation Institution University of Utah
Dissertation Name Doctor of Philosophy
Language eng
Rights Management Copyright © Thomas Grant McNary 2011
Format Medium application/pdf
Format Extent 1,397,972 Bytes
Identifier etd3/id/3506
ARK ark:/87278/s6j70r6p
Setname ir_etd
Date Created 2015-05-21
Date Modified 2017-11-07
ID 197059
Reference URL https://collections.lib.utah.edu/ark:/87278/s6j70r6p