期刊
BIOPHYSICAL JOURNAL
卷 86, 期 1, 页码 359-370出版社
BIOPHYSICAL SOCIETY
DOI: 10.1016/S0006-3495(04)74112-0
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- NATIONAL INSTITUTE OF ARTHRITIS AND MUSCULOSKELETAL AND SKIN DISEASES [Z01AR041122, Z01AR041118, ZIAAR041122, ZIAAR041118] Funding Source: NIH RePORTER
To investigate the interplay between the thin and thick. laments during calcium activation in striated muscle, we employed n-(6-aminohexyl)5-chloro-1-napthalenesulfonamide(W7) as an inhibitor of troponin C and compared its effects with that of the myosin-specific inhibitor, 2,3-butanedione 2-monoxime (BDM). In both skeletal and cardiac fibers, W7 reversibly inhibited ATPase and tension over the full range of calcium activation between pCa 8.0 and 4.5, resulting in reduced calcium sensitivity and cooperativity of ATPase and tension activations. At maximal activation in skeletal fibers, the W7 concentrations for half-maximal inhibition (K-I) were 70-80 muM for ATPase and 20-30 muM for tension, nearly >200-fold lower than BDM (20 mM and 5-8 mM, respectively). When W7 (50 muM) and BDM (20 mM) were combined in skeletal fibers, the ATPase and tension-pCa curves exhibited lower apparent cooperativity and maxima and higher calcium sensitivity than expected from two independent activation pathways, suggesting that the interplay between the thin and thick. laments varies with the level of activation. Significantly, the inhibition of W7 increased the ATPase/tension ratio during activation in both muscle types. W7 holds much promise as a potent and reversible inhibitor of thin. lament-mediated calcium activation of skeletal and cardiac muscle contraction.
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