Key Points
- To review the enzymatic steps and regulatory mechanisms governing actin-myosin cross-bridge kinetics, force generation, and shortening velocity in smooth muscle fibres.
- Synthesized experimental findings from chemically skinned smooth muscle preparations correlating mechanical performance with biochemical states.
- Evaluated the impact of nucleotide binding, phosphate release, and regulatory light chain phosphorylation on cross-bridge cycling rates.
- ATP binding dissociates rigor cross-bridges without being rate-limiting, while tight ADP binding to myosin contributes to characteristic slow cross-bridge turnover.
- Inorganic phosphate release drives force generation, and recruitment of slowly cycling dephosphorylated cross-bridges reduces maximal shortening velocity during low activation.
- Tissue-specific diversity and long-term adaptation of shortening velocity are regulated by shifts in myosin heavy and light chain isoform expression.
Structured PICO
PPopulationSmooth muscle fibres (chemically skinned preparations)
This review summarizes the mechanisms of cross-bridge cycling in smooth muscle, highlighting the roles of ATP, Pi, and ADP in force generation and shortening velocity.