Fig. 3. Inhibition of actomyosin interaction or Rho-kinase diminishes the mechanical response of cells to shear flow. Cells were pretreated with BDM (20 mM) for 30 minutes to inhibit actomyosin interactions, and were either left unsheared (A) or sheared (B) for 40 minutes. Phase-contrast micrographs show minor changes in cell area and shape. Bar, 20 µm. Mean cellular compliances of unsheared fibroblasts (n=3) were similar after 40 minutes of BDM treatment. BDM treatment and shear flow caused fibroblasts to stiffen, but considerably less compared with control conditions, as shown by mean cellular compliances of sheared fibroblasts (n=4). Cells were also pretreated with specific Rho-kinase inhibitor Y-27632 (30 µM) for 30 minutes and were either left unsheared (C) or sheared (D) for 40 minutes. Phase-contrast micrographs show minor changes in cell area and shape. Bar, 20 µm. Mean cellular compliances of unsheared fibroblasts (n=3) were similar after 40 minutes of drug treatment. However, mean cellular compliances of sheared fibroblasts (n=4) show that cells did not stiffen in response to shear flow, and even became softer. All values represent mean ± s.e.m.