Mechanical and Contractile Properties of Isolated Single Intact Cardiac Cells
During the last 20 years a great deal of effort has been expended attempting to define cardiac muscle contractile performance in terms of the performance of the sarcomere within the cardiac muscle. The early studies of cardiac contractile performance assessed sarcomere performance indirectly due to the inherent difficulties of directly visualizing the sarcomeres in most intact cardiac preparations. In order to assign certain contractile properties (e.g., force and velocity) of the intact tissue to the so-called contractile element (i.e., sarcomere) within the tissue it was necessary to use mechanical equivalent models (the so-called Maxwell or Voigt models) composed of a contractile element and at least two elastic elements: parallel and series elastic. By the mid 1970’s it was generally accepted that such attempts to deduce sarcomere performance from whole tissue performance would yield questionable results due to 1) the uncertainties in quantitating the physical properties of the intact tissue as represented by equivalent series and parallel elastic elements, 2) the inability of any unique mechanical model to represent both the static and dynamic contractile properties of heart muscle, and 3) the dramatic nonuniformities in the distribution of structures (elastic and contractile) within the intact muscle.
KeywordsCardiac Cell Sarcomere Length Contractile Property Glass Beam Cardiac Sarcomere
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