Document Detail

Gel stretch method: a new method to measure constitutive properties of cardiac muscle cells.
MedLine Citation:
PMID:  9841544     Owner:  NLM     Status:  MEDLINE    
Diastolic dysfunction is an important cause of congestive heart failure; however, the basic mechanisms causing diastolic congestive heart failure are not fully understood, especially the role of the cardiac muscle cell, or cardiocyte, in this process. Before the role of the cardiocyte in this pathophysiology can be defined, methods for measuring cardiocyte constitutive properties must be developed and validated. Thus this study was designed to evaluate a new method to characterize cardiocyte constitutive properties, the gel stretch method. Cardiocytes were isolated enzymatically from normal feline hearts and embedded in a 2% agarose gel containing HEPES-Krebs buffer and laminin. This gel was cast in a shape that allowed it to be placed in a stretching device. The ends of the gel were held between a movable roller and fixed plates that acted as mandibles. Distance between the right and left mandibles was increased using a stepper motor system. The force applied to the gel was measured by a force transducer. The resultant cardiocyte strain was determined by imaging the cells with a microscope, capturing the images with a CCD camera, and measuring cardiocyte and sarcomere length changes. Cardiocyte stress was characterized with a finite-element method. These measurements of cardiocyte stress and strain were used to determine cardiocyte stiffness. Two variables affecting cardiocyte stiffness were measured, the passive elastic spring and viscous damping. The passive spring was assessed by increasing the force on the gel at 1 g/min, modeling the resultant stress vs. strain relationship as an exponential [sigma = A/k(ekepsilon - 1)]. In normal cardiocytes, A = 23.0 kN/m2 and k = 16. Viscous damping was assessed by examining the loop area between the stress vs. strain relationship during 1 g/min increases and decreases in force. Normal cardiocytes had a finite loop area = 1.39 kN/m2, indicating the presence of viscous damping. Thus the gel stretch method provided accurate measurements of cardiocyte constitutive properties. These measurements have allowed the first quantitative assessment of passive elastic spring properties and viscous damping in normal mammalian cardiocytes.
M R Zile; M K Cowles; J M Buckley; K Richardson; B A Cowles; C F Baicu; I V Cooper G; V Gharpuray
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  274     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1998 Jun 
Date Detail:
Created Date:  1998-11-05     Completed Date:  1998-11-05     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  H2188-202     Citation Subset:  IM; S    
Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston, SC 29401, USA.
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MeSH Terms
Calcium / pharmacology
Cell Adhesion
Cell Physiological Phenomena
Cell Size
Cell Survival
Diacetyl / analogs & derivatives,  pharmacology
Egtazic Acid / pharmacology
Gels / chemistry
Myocardium / cytology*
Sepharose / chemistry
Tensile Strength
Grant Support
Reg. No./Substance:
0/Gels; 431-03-8/Diacetyl; 57-71-6/diacetylmonoxime; 67-42-5/Egtazic Acid; 7440-70-2/Calcium; 9012-36-6/Sepharose
M R Zile / Med U SC, Charleston

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