Impedance actin cytoskeleton

Fig. 12 Fluorescence micrographs of confluent MDCK II cell monolayers after the actin cytoskeleton has been stained by fluorescence-labeled phalloidin. a Control cells were not exposed to Cytochalasin D. b Cells were exposed to 5 xM Cytochalasin D for 100 min. The staining confirms that actin filaments have been degraded to small actin aggregates. The scale bar represents 25 xm. c Magnitude of the load impedance A 2l as a function of time when confluent MDCK II cell monolayers were exposed to 5 xM Cytochalasin D at the time indicated by the arrow. The value of Zi at the beginning of the experiment was set to zero...

Treating cells with CD to disassemble their actin cytoskeleton has been described many times in the literature. When cells were studied by scanning force microscopy (SFM) after CD exposure, a significant reduction of membrane stiffness was reported for various cell types [41,42]. Since the acoustic impedance also decreases, it seems reasonable to propose that the QCM may serve as a micromechanical probe to study membrane stiffness. Further experiments will be presented below that support this point of view. 

Fig. 15 Attachment, spreading, and differentiation of MDCK II cells followed by the combined QCM-ECIS approach. The change in load impedance A Zl (open circles) reports on attachment, spreading, and reorganization of the actin cytoskeleton. The electrical impedance at 400 Hz (filled symbols) mirrors the establishment of barrier-forming cellcell contacts and, thus, differentiation. The fluorescence micrographs in the right panel visualize the status of the actin cytoskeleton 3 h and 10 h after cell seeding. These time points are indicated in the graph by the dashed lines marked as 1 and 2...

Activation of CKRs leads to the modulation of the actin cytoskeleton and consequently changes cell morphology and cell adhesion. These changes can be measured by changes in electrical resistance (impedance) at the interface... 

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