Effects of cytochalasin D and latrunculin B on mechanical properties of cells

Actin microfilaments transmit traction and contraction forces generated wit hin a cell to the extracellular matrix during embryonic development, wound healing and cell motility, and to maintain tissue structure and tone. There fore, the state of the actin cytoskeleton strongly influences the mechanica l properties of cells and tissues. Cytochalasin D and Latrunculin are commo nly used reagents that, by different mechanisms, alter the state of actin p olymerization or the organization of actin filaments. We have investigated the effect of a wide range of Cytochalasin D and Latrunculin B concentratio ns (from 40 pM to 10 muM) on the mechanical properties of the cells within fibroblast populated collagen matrices, Contractile force and dynamic stiff ness were measured by uniaxial stress-strain testing. The range of effectiv e concentrations of Cytochalasin D (200 pM-2 muM) was broader than that of Latrunculin B (20 nM-200 nM), Activating the cells by serum did not change the effective range of Cytochalasin D concentrations but shifted that of La trunculin B upward by tenfold, Simple mathematical binding models based on the presumed mechanisms of action of Cytochalasin D and Latrunculin B simul ated the concentration-dependent mechanical changes reasonably well, This s tudy shows a strong dependence of the mechanical properties of cells and ti ssues on the organization and degree of polymerization of actin filaments.