Constitutive properties of hypertrophied myocardium: cellular contribution to changes in myocardial stiffness.
Recent studies have suggested that pressure overload hypertrophy (POH) alters the viscoelastic properties of individual cardiocytes when studied in isolation. However, whether these changes in cardiocyte properties contribute causally to changes in the material properties of the cardiac muscle as a whole is unknown. Accordingly, a selective, isolated, acute change in cardiocyte constitutive properties was imposed in an in vitro system capable of measuring the resultant effect on the material properties of the composite cardiac muscle. POH caused an increase in both myocardial elastic stiffness, from 20.5 +/- 1.3 to 28.4 +/- 1.8, and viscous damping, from 15.2 +/- 1.1 to 19.8 +/- 1.5 s (normal vs. POH, P < 0.05), respectively. Recent studies have shown that cardiocyte constitutive properties could be acutely altered by depolymerizing the microtubules with colchicine. Colchicine caused a significant decrease in the viscous damping in POH muscles (19.8 +/- 1.5 s at baseline vs. 14.7 +/- 1.3 s after colchicine, P < 0.05). Therefore, myocardial material properties can be altered by selectively changing the constitutive properties of one element within this muscle tissue, the cardiocyte. Changes in the constitutive properties of the cardiocytes themselves contribute to the abnormalities in myocardial stiffness and viscosity that develop during POH.
Harris
Todd S
TS
Cardiology Section, Department of Medicine, and Gazes Cardiac Research Institute, Medical University of South Carolina and Veterans Administration Medical Center, Charleston, South Carolina 29401, USA.
Baicu
Catalin F
CF
Conrad
Chester H
CH
Koide
Masaaki
M
Buckley
J Michael
JM
Barnes
Mary
M
Cooper
George
G
Zile
Michael R
MR
D000818:Animals; D001696:Biomechanical Phenomena; D006332:Cardiomegaly / Q000503:physiopathology*; D002415:Cats; D003078:Colchicine / Q000494:pharmacology; D004548:Elasticity; D006321:Heart / Q000503:physiopathology*; D006439:Hemodynamics; D008870:Microtubules / Q000187:drug effects / Q000502:physiology; D009206:Myocardium / Q000648:ultrastructure; D011312:Pressure; D014783:Viscosity
D003078:Colchicine