PMC

Force buildup in two axons after unloading. Part A corresponds to the axon whose loading curve is shown in A. Note that the tension in the axon after force buildup (1.77 nN) was close to its rest tension (2 nN). The tension in the axon shown in B after force buildup (2.77 nN) was lower than its rest tension (4.21 nN).

T_Load is greater than T_Unload in permeabilized detrusor smooth muscle (DSM). A: loading (Load) and unloading (UL) protocol used to determine the length dependencies of passive tension. B: example of a passive tension tracing of permeabilized DSM subjected to the protocol shown in A. C: summary data showing that for each length step, the tension values produced on muscle loading were greater than those produced on unloading. T_L4, pseudo steady-state tension value at the 4th loading length. Data in C are means ± SE, n = 3. *P < 0.05 compared with T_Load, Student's t-test.

The tension was normalized by cross-sectional area of the muscle. The values shown are means ± SEM. **P < 0.01 vs. control. (A) Maximum tetanic tension under continuous high frequency stimulation. n = 6 muscles in each group. (B) Maximum tetanic tension under intermittent stimulation. n = 6 muscles in each group.

Unloading of an EDLat tendon by a MU. Simultaneous tension records of EDLat’s three tendons are shown during a single twitch (A) and during tetanic stimulation at 20 Hz (B, C) of a single MU that unloaded the t4 tendon while exerting tension on the t3 and t5 tendons. In the single twitch (A) and in the high gain record (C), tension in the t4 tendon can be seen to decrease with each increase in tension in the other two tendons. Horizontal calibration bar = 0.5 sec; vertical calibration bar = 1.51 gm-wt in A, 2.36 gm-wt in B, 0.30 gm-wt in C.