Dependence of elastic and viscous properties of elastic arteries on circumferential wall stress at two different smooth muscle tones

Using isolated segments of the abdominal aorta of normotensive rats, the dependence of the dynamic circumferential elastic modulus (Ed), the loss modulus (ωηw), and and the coefficient of wall viscosity (ωηw) on the mean circumferential wall stress (σt) and the frequency of radius changes were studied under conditions of strong smooth muscle activation, induced by norepinephrine (NE), and during relaxation, induced by papaverine (PAP). The arterial segments were subjected to quasistatic and to small sinusoidal volume changes of 0.1–20 Hz at mean pressure levels of 1–23 kPa. The diameter changes were recorded by means of a photoelectric device with high spatial and temporal resolution.Ed, ωηw, and ηw were calculated from the mean external and internal radii and from the dynamic pressure-radius changes determined at each pressure level.