BDM compared with P(i) and low Ca2+ in the cross-bridge reaction initiated by flash photolysis of caged ATP.
AUTOR(ES)
Kagawa, K
RESUMO
Using flash photolysis of caged ATP in skinned muscle fibers from rat psoas, we examined the inhibitory effects of 2,3-butanedione monoxime (BDM) on the contraction kinetics and the rate of ATP hydrolysis of the cross-bridges at approximately 10 degrees C. The hydrolysis rate was estimated from the stiffness records. The effects of BDM were compared with those of orthophosphate (P(i)) and of reduction in [Ca2+] (low Ca2+), and it was found that i) BDM and low Ca2+ inhibited ATPase activity to the same extent as they inhibited the steady tension, whereas P(i) inhibited ATPase activity much less than tension; ii) BDM and P(i) decreased tension per stiffness during the steady contraction more than did low Ca2+; iii) neither BDM nor low Ca2+ affected the initial relaxation of the fiber on release of ATP, but P(i) slightly slowed it; and iv) BDM hardly influenced the rate of contraction development after relaxation, although P(i) and low Ca2+ accelerated it. We concluded that BDM inhibits the Ca(2+)-regulated attachment of the cross-bridges and force-generation of the attached cross-bridges.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1236497Documentos Relacionados
- Cross-bridge kinetics in the presence of MgADP investigated by photolysis of caged ATP in rabbit psoas muscle fibres.
- Flash and smash: rapid freezing of muscle fibers activated by photolysis of caged ATP.
- The effects of MgADP on cross-bridge kinetics: a laser flash photolysis study of guinea-pig smooth muscle.
- Modulation of cross-bridge affinity for MgGTP by Ca2+ in skinned fibers of rabbit psoas muscle.
- Ca2+ release from the sarcoplasmic reticulum of barnacle myofibrillar bundles initiated by photolysis of caged Ca2+.