FLUCTUATING SHEAR-STRESS EFFECTS ON STRESS FIBER ARCHITECTURE AND ENERGY-METABOLISM OF CULTURED RENAL-CELLS

The project investigates the relationship between the external shear f orce and the actin cytoskeleton along with the metabolic changes occur ring inside the cells due to this force. Anchorage-dependent Madin Dar by canine kidney (MDCK) cells were placed in spinner flasks with paddl e-type stirrers agitated at 20 rpm, where they experienced shear stres s fluctuations from 0.02 to 0.27 dyn/cm(2) in magnitude. Following fix ation, permeabilization, and staining with rhodamine-phalloidin, the r elative amounts and distribution of F-actin stress fibers in the 1 mu m basal layer of the cells were visualized by confocal microscopy. The se structures disappeared after 12-15 h of exposure to shear stress. P revious results showed that the stress fibers disappear, leading to lo ss of epithelial attachment, after only 1 h of starvation-induced ener gy depletion. Therefore, in this study, the energy metabolism of the c ells was established by measuring adenosine triphosphate (ATP) levels at different time intervals. No statistical difference in ATP content was found between the shear-stressed cells and the controls, showing t hat shear stresses cause cytoskeletal reorganization by a mechanism ot her than ATP depletion.