Role of Ca2+ and myosin light chain phosphorylation in regulation of smooth muscle.
Role of Ca2+ and myosin light chain phosphorylation in regulation of smooth muscle.
复制标题
Ca2 和肌球蛋白轻链磷酸化在平滑肌调节中的作用。
DOI：
10.1152/ajpcell.1982.242.1.c109
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发表时间：
1982
期刊：
影响因子：
--
通讯作者：
Kamm,KE
中科院分区：
文献类型：
--
作者：
Aksoy,MO;Murphy,RA;Kamm,KE
在K+和组胺刺激的猪颈动脉内侧条收缩和舒张期间，测定了20，000-道尔顿肌球蛋白轻链（LC 20）磷酸化的时间过程。静息LC 20磷酸化水平为0.15 mol P/mol LC 20，刺激后迅速升高至峰值0.6-0.7 mol P/mol LC 20，然后显著下降，尽管应激继续升高至稳定的稳态最大值。激动剂洗脱后LC 20去磷酸化先于等长应力下降。在整个收缩-舒张周期中，磷酸化与缩短速度相关，而与应力无关。无外负荷时的最大缩短速度（Vo）与LC 20磷酸化水平成正比（r = 0.986）。这些数据表明，LC 20磷酸化是必要的跨桥循环，导致缩短或应力发展，但应力可以保持额外的机制。我们认为，在钙离子存在下，附着的跨桥的去磷酸化逮捕的周期，形成一个附加的，noncycling跨桥。
The time course of phosphorylation of the 20,000-dalton myosin light chain (LC 20) was determined during contraction and relaxation in K+- and histamine-stimulated medial strips of swine carotid arteries. Resting LC 20 phosphorylation levels of 0.15 mol P/mol LC 20 rapidly increased to peak values of 0.6-0.7 mol P/mol LC 20 after stimulation and then declined significantly, although stress continued to rise to a stable steady-state maximum. LC 20 dephosphorylation after agonist washout preceded the decline in isometric stress. Over the entire contraction-relaxation cycle, phosphorylation was correlated with shortening velocity and not with developed stress. The maximum shortening velocity with no external load (Vo) was directly proportional to LC 20 phosphorylation (r = 0.986). The data indicate that LC 20 phosphorylation is necessary for cross-bridge cycling leading to shortening or stress development but that stress can be maintained by additional mechanisms. We suggest that dephosphorylation of an attached cross bridge in the presence of Ca2+ arrests the cycle, forming an attached, noncycling cross bridge.