Myosin light chain phosphorylation during phasic contractions of tracheal smooth muscle.
Myosin light chain phosphorylation during phasic contractions of tracheal smooth muscle.
复制标题
气管平滑肌阶段性收缩期间肌球蛋白轻链磷酸化。
DOI：
10.1007/bf00585071
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
Kamm,KE
中科院分区：
文献类型：
--
作者：
Kamm,KE
气管平滑肌的快速、协调收缩可由肌细胞的直接电去极化或四乙基铵引起的自发相收缩活动引起。这两种类型的收缩都被钙通道拮抗剂维拉帕米阻断，表明这些收缩主要是由细胞外来源的钙支持的。在直接电刺激下，肌球蛋白可磷酸化轻链（P-light chain）的磷酸盐含量从0.1 mol磷酸盐/mol P-light chain迅速增加（~ 2.5 s），然后下降到高于静息值的水平。磷酸化比力的增加更快。在自发活动的条件下，相收缩发生在明显大于静息力的基础张力水平以上，并且在收缩基础处测量的磷酸化最小值明显大于静息肌。磷酸化随力振荡（从0.2 ~ 0.4 mol磷酸/mol p -轻链），峰值出现在收缩上升期。磷酸化和力的时间过程表明肌球蛋白在去磷酸化后的激活状态延长。这些结果表明，肌球蛋白p -轻链的磷酸化和去磷酸化足够快，参与了相性机械活动中收缩性的调节。
Rapid, coordinated contractions of tracheal smooth muscle were elicited by either direct electrical depolarization of muscle cells or treatment with tetraethylammonium which produced spontaneous phasic contractile activity. Both types of contraction were blocked by the calcium channel antagonist verapamil, indicating that these contractions are supported primarily by calcium of extracellular origin. With direct electrical stimulation, force was biphasic and phosphate content of the phosphorylatable light chain (P-light chain) of myosin increased rapidly (∼2.5 s) from 0.1 to 0.4 mol phosphate/mol P-light chain, then decreased to levels above resting values. Phosphorylation increased more rapidly than force. Under conditions of spontaneous activity, phasic contractions occurred above a level of basal tone significantly greater than resting force, and minimum values of phosphorylation measured at the base of contraction were significantly greater than those observed in the resting muscle. Phosphorylation oscillated with force (from 0.2 to 0.4 mol phosphate/mol P-light chain) and peak values occurred during the rising phase of contraction. Time courses of phosphorylation and force showed evidence of a prolonged state of activation of myosin following dephosphorylation. These results suggest that phosphorylation and dephosphorylation of myosin P-light chain are sufficiently rapid to participate in regulation of contractility during phasic mechanical activity.