Fig. 1.

A: sample data illustrating the tension measurement protocol. Detrusor smooth muscle (DSM) strips were incubated for 2 min in Ca²⁺-free solution (0 Ca); stretched or released to the muscle length of interest, if necessary; incubated for an additional 2 min in 0 Ca; incubated in modified physiological salt solution (PSS) for 3 min; and then incubated in PSS modified to include KCl rather than NaCl (KPSS) for 1 min to induce a contraction. T, tension; Tpeak, peak tension. B: reference length (L_ref) identification protocol. Passive tension (Tp) and active tension (Ta) were measured at each length in a sequence of 3-mm steps from 3 mm to 12, 15, or 18 mm until a peak in the L-Ta curve was identified, and the corresponding length was designated as L_ref. C: sample data from 3 tissues with L_ref at 9 (●), 12 (▴), and 15 mm (■), respectively. Ta_max, maximum active tension.