Abstract
It is known that number of the thick and thin filaments in tracheal smooth muscles increases by activation with Ca2+ (Seow, 2005), while the content of contractile filaments does not change during relaxation-contraction cycles in smooth muscles of taenia caeci from guinea pig (e.g. Watanabe et al., 1993). Therefore, organization of the contractile filaments in taenia caeci and trachea might be regulated by different mechanisms. To test this possibility, we studied the effects of blebbistain, which suppressed contraction and disrupted thick and thin filaments organization of skinned (cell membrane permeabilizsed) taenia caeci (Watanabe et al., 2007), on the mechanical responses of the skinned preparations of tracheal smooth muscles from guinea pig. Compared with the blebbistatin effects on the skinned taenia caeci, much lower concentrations of the agent induced inhibition of contraction in skinned trachea. These results indicated that blebbistatin might accelerate myosin filaments dissociation in tracheal smooth muscles. Contribution of myosin ATPase activity to myosin filaments assembly and disassembly in smooth muscle will be discussed. [J Physiol Sci. 2008;58 Suppl:S67]
