Blebbistatin effectively and dose-dependently relaxes both KCl- and carbachol-induced rat detrusor contractions as well as endothelin-1-induced human bladder contractions. Pre-incubation with 10 μM blebbistatin reduces carbachol responsiveness by 65% and inhibits electrical field stimulation-induced bladder contraction by 50% at 32 Hz^[4].

Blebbistatin effectively inhibits various striated muscle myosins and vertebrate nonmuscle myosin IIA and IIB, with IC50 values between 0.5 to 5 μM. It exhibits much weaker inhibition of smooth muscle myosin, with an IC50 of 80 μM^[1].

Blebbistatin does not interfere with nucleotide binding to the skeletal muscle myosin subfragment-1. Instead, it preferentially binds to the ATPase intermediate that has ADP and phosphate at the active site, thereby slowing down phosphate release. This inhibitor traps the myosin heads in a products complex that exhibits low affinity for actin^[2].

In culture-activated hepatic stellate cells, blebbistatin alters cell morphology and function. The stellate cells become smaller, develop a dendritic morphology, and show fewer myosin IIA-containing stress fibers and vinculin-containing focal adhesions. Blebbistatin hinders silicone wrinkle formation, diminishes collagen gel contraction, and blocks endothelin-1-induced intracellular Ca²⁺ release. Additionally, it enhances wound-induced cell migration^[3].