Fig. 2.

Axial first Piola-Kirchhoff stress (T_zz) as a function of λ_θ at λ_z of 1.2 (A) and 1.3 (B) measured at K⁺-induced contraction and Ca²⁺-free-induced vasodilation. Shown are total stress (□): ${\left[\frac{F}{{\lambda }_z\pi \left(r_o^2-r_{\text{i}}^2\right)}+\frac{{\mathrm{Pr}}_i^2}{{\lambda }_{z}h\left(r_{\text{o}}+r_{\text{i}}\right)}\right]}_{\text{total}}$ at contraction; passive stress (△): ${\left[\frac{F}{{\lambda }_z\pi \left(r_o^2-r_{\text{i}}^2\right)}+\frac{{\mathrm{Pr}}_i^2}{{\lambda }_{z}h\left(r_{\text{o}}+r_{\text{i}}\right)}\right]}_{\text{passive}}$ at vasodilation; and active stress (thin solid line): ${\left[\frac{F}{{\lambda }_z\pi \left(r_o^2-r_{\text{i}}^2\right)}+\frac{{\mathrm{Pr}}_i^2}{{\lambda }_{z}h\left(r_{\text{o}}+r_{\text{i}}\right)}\right]}_{\text{total}}{\left[\frac{F}{{\lambda }_z\pi \left(r_o^2-r_{\text{i}}^2\right)}+\frac{{\mathrm{Pr}}_i^2}{{\lambda }_{z}h\left(r_{\text{o}}+r_{\text{i}}\right)}\right]}_{\text{passive}}$. The thick dotted, dashed, and solid lines refer to the theoretical total, passive, and active stresses, respectively.