Figure 1.

Representative tracings of length (L) and force (F) for vehicle control and latrunculin B–treated canine tracheal smooth muscle (TSM) strips. (A) These tracings are compressed to visualize and compare before and after treatment of TSM strips with either vehicle (control or latrunculin B). After determining the maximum isometric response to 100 μM ACh (Fmax), muscles were isotonically contracted from Lref against a load = 32% Fmax again using 100 μM ACh. Superimposed force oscillations (± 16% Fmax) caused tissue relengthening that was significantly augmented in the presence of 30 nM latrunculin B (lower panels) compared with vehicle controls (upper panels). (B) This trace is a blowup of the pre–latrunculin B protocol length myogram at left. The following length parameters were noted and comparisons made between treatments, before and after interventions: maximal isotonic shortening, spontaneous relengthening, and force oscillation–induced relengthening. (Reprinted by permission from Reference 1.)