Effects of cytoskeletons on tensile properties of cultured aortic smooth muscle cells obtained in a quasi-in situ tensile test

摘要

Effects of actin filaments (AFs) and microtubules (MTs) on quasi-in situ tensile properties and internal tension at a whole-cell level were studied in rat aortic smooth muscle cells (SMCs) cultured on substrates. SMCs were held with a pair of micropipettes maintaining their shape on the substrate. Tensile tests up to ～10% strain were performed for 3-4 times both before and after administration of cytochalasin D or colchicine. Force-elongation curves became stable after second cycle of loading/unloading process. The cell stiffness defined as the average slope of loading curve in stable loops were decreased by ～70% after AF disruption with cytochalasin D. Treatment with colchicine, a MT disrupter, decreased cell stiffness by ～30%. The cell height significantly increased with AF disruption, while it decreased with MT disruption. These results indicate that not only AFs but also MTs play crucial roles in maintaining whole-cell stiffness of SMCs, and while AFs act as an internal tension generator, MTs may act as a tension reducer.