Measurement of some viscoelastic properties of rat skin following repeated load.

The influence of age and of corticosteroid treatment on viscoelastic properties of skin samples has been studied in rats. Hysteresis curves were evaluated with increased extension for each cycle. Maximum stress and modulus of elasticity were increased by age and by 10 days' prednisolone treatment. However, hysteresis indicating viscous properties measured by the ratio of energy dissipation versus energy input was only slightly decreased by age and almost unchanged by prednisolone treatment. The same holds true for the residual extension, another parameter of viscosity. In another experimental series the effects of repeated loading were studied. Again the parameters indicating elasticity were increased by age and prednisolone treatment but the parameters of viscosity were only slightly decreased by age.