Calponin (4.1-5.9 microM, pig stomach) inhibited maximal shortening velocity (Vmax) by 20-25% with only minor influence on force in skinned smooth muscle from guinea-pig taenia coli activated at different Ca2+ levels and with thiophosphorylation. Similar results were obtained with a fragment of the N-terminal 1-228 amino acids engineered using a mouse cDNA construct (5.4 microM). Both the native calponin and the fragment inhibited actin filament sliding in a graded manner in an in vitro motility assay. We conclude that calponin influences the kinetics of the actin-myosin interaction in the organised smooth muscle contractile system and that engineered fragments of calponin can be used to probe its action in muscle fibres. The effects can be due to an introduction of an internal load during filament sliding, possibly by decreasing the detachment rates and increasing the cross-bridge time spent in the attached state.
Useful keywords (using NLM MeSH Indexing)
Dose-Response Relationship, Drug
Isometric Contraction/drug effects*
Muscle Fibers, Skeletal/drug effects
Muscle Fibers, Skeletal/physiology*
Muscle, Smooth/drug effects
Find related publications in this database (Keywords)CALPONIN