Abstract
Tensile properties of contracted and relaxed vascular smooth muscle cells (VSMCs) were determined. VSMCs were isolated from the rabbit thoracic aorta with an enzymatic digestion method. Each cell floated in Hanks' balanced salt solution of 37 ℃ was attached to the fine tips of a pair of micropipettes with an urethane resin, and contracted and relaxed with norepinephrine and papaverine, respectively. Then the cell was stretched at the rate of 6μm/sec by moving one of the micropipettes with a linear actuator. Load applied to the cell was measured with a cantilever-type load cell : its elongation was determined from the distance between the micropipette tips using a video dimension analyzer. Activated (contracted) and passive (relaxed) VSMC_s were not broken even at the tensile force of 6.5μN and 1.7μN, respectively. Their stiffness was significantly higher under activated condition (0.89N/m) than under passive one (0.14N/m). The higher stiffness in contracted cells is attributable to the tension generated by contractile apparatus and reorganization of actin filaments.
