Quantitative measurements of active and passive mechanical properties of adult cardiac myocytes

We have developed novel methods to examine the effects of mutations in sarcomeric proteins on the mechanical properties of single adult mouse cardiac myocytes. Magnetic tweezers are used to apply forces to microscopic beads attached to the cell surface. High resolution image processing algorithms allow mapping of cytoskeletal displacement, tracking single sarcomere positions, and monitoring bead displacements in response to the applied forces. Active force generation, passive cellular stiffness and the mechanical coupling between the cytoskeleton and the extracellular environment can be quantitatively inferred from these measurements.