BIAXIAL ELASTIC PROPERTIES OF RAT ARTERIES IN-VIVO - INFLUENCE OF VASCULAR WALL CELLS ON ANISOTROPY

There is no consensus as to the degree of arterial anisotropy or to it s relationship to vascular cell function. Given the relevance of the i sotropic assumption in formulating elasticity models, reliable measure s of biaxial displacements are needed. In this study, a video motion a nalyzer (VMA) was used to describe the biaxial in vivo dynamic elastic ity of 22 carotid arteries and 5 abdominal aortas in 27 rats. The infl uence of vascular cell function was also examined by subjecting six ra ts to a photosensitive drug, chloroaluminum sulfonated phthalocyanine (CASPc), which is focally cytotoxic on activation by laser. Circumfere ntial compliance (C-circ) was greater than longitudinal compliance (C- long) for all vessels. Compliance pressure curves were nonlinear, and biaxial displacements were in phase. The circumferential elastic modul us was less than the longitudinal modulus at common stresses. CASPc laser reduced C-circ but not C-long, thus altering Poisson's ratio. In conclusion, rat arteries are biaxially, nonlinearly elastic and aniso tropic in vivo. Vascular cells modulate Poisson's ratio by influencing C-circ.