Atomic force microscopic measurement of the mechanical properties of intact endothelial cells in fresh arteries

Mechanical properties of living endothelial cells in the abdominal aortas and in the medial and lateral wall of aortic bifurcations obtained from rabbits were determined by means of an atomic force microscope (AFM), focusing on the locational differences. Force (F)-indentation (delta) curves of the cells were expressed by an exponential function: F = a(exp(b delta)-1), where a and b are constants. The parameters b and c(= ab) represent the rate of modulus change and initial modulus, respectively. The slope of F-S curves a and the parameter c were higher in the medial wall than in the other sites, which is attributable to abundant stress fibres in endothelial cells in the medial wall. There were no differences in the parameter b among the three locations. These results indicate that endothelial cells are stiffer in the medial wall of aortic bifurcation than in the other regions.