Skeletal muscle force and actomyosin ATPase activity reduced by nitric oxide donor
Skeletal muscle force and actomyosin ATPase activity reduced by nitric oxide donor
复制标题
DOI：
10.1152/jappl.1997.83.4.1326
复制
发表时间：
1997-10-01
影响因子：
3.3
通讯作者：
Sieck, GC
中科院分区：
文献类型：
--
作者：
Perkins, WJ;Han, YS;Sieck, GC
一氧化氮（NO）可能通过调节肌球蛋白头部的关键硫醇对肌动蛋白-肌球蛋白跨桥循环产生直接影响。在本研究中，确定了 NO 供体硝普钠（SNP；100 μM 至 10 mM）对兔腰肌单根透化肌纤维的机械特性和肌动球蛋白腺苷三磷酸酶 (ATPase) 活性的影响。还评估了硫醇特异性烷基化试剂 N-乙基马来酰亚胺（NEM；5-250 μM）对单纤维机械性能的影响。 NEM（大于或等于25μM）和SNP（大于或等于1mM）均显着抑制等长力和肌动球蛋白ATP酶活性。 SNP 处理的单纤维的无负载缩短速度有所降低，但程度较小，表明 SNP 对等长力和肌动球蛋白 ATP 酶的影响很大程度上是由于跨桥招募减少。经过 SNP 处理的单纤维的钙敏感性也降低了。通过用 10 mM DL-二硫苏糖醇（一种硫醇还原剂）处理，可以逆转 SNP（而非 NEM）对力和肌动球蛋白 ATP 酶活性的影响。我们得出结论，NO 供体 SNP 抑制由收缩蛋白硫醇可逆氧化引起的收缩功能。
Nitric oxide (NO) may exert direct effects on actin-myosin cross-bridge cycling by modulating critical thiols on the myosin head. In the present study, the effects of the NO donor sodium nitroprusside (SNP; 100 mu M to 10 mM) on mechanical properties and actomyosin adenosinetriphosphatase (ATPase) activity of single permeabilized muscle fibers from the rabbit psoas muscle were determined. The effects of N-ethylmaleimide (NEM; 5-250 mu M), a thiol-specific alkylating reagent, on mechanical properties of single fibers were also evaluated. Both NEM (greater than or equal to 25 mu M) and SNP (greater than or equal to 1 mM) significantly inhibited isometric force and actomyosin ATPase activity. The unloaded shortening velocity of SNP-treated single fibers was decreased, but to a lesser extent, suggesting that SNP effects on isometric force and actomyosin ATPase were largely due to decreased cross-bridge recruitment. The calcium sensitivity of SNP-treated single fibers was also decreased. The effects of SNP, but not NEM, on force and actomyosin ATPase activity were reversed by treatment with 10 mM DL-dithiothreitol, a thiol-reducing agent. We conclude that the NO donor SNP inhibits contractile function caused by reversible oxidation of contractile protein thiols.