Passive elastic properties of the rat abdominal vena cava

The quasistatic passive venous elastic properties were studied in-vitro on 6 cylindrical segments of abdominal vena cava from Wistar rats. Using noncontact methods of deformation measurement, diameter and axial force of the segments were analyzed as a function of simultaneous axial stretch and internal pressure in the physiological range of 0-2.7 kPa. The elasticity of the wall tissue was investigated in terms of moduli of elasticity in the circumferential, axial and radial directions. Results show that the pressure-diameter relationship is highly nonlinear, indicating that veins are extremely compliant at lowest pressures and rather stiff beginning from some 0.7 kPa of pressure. The axial force decreases with pressure at small prestretches, increases at large, but remains constant for the in-vivo prestretch. The venous wall tissue is markedly anisotropic in the entire physiological range of deformations.