Inhibition of CaM kinase II activation and force maintenance by KN-93 in arterial smooth muscle.
Inhibition of CaM kinase II activation and force maintenance by KN-93 in arterial smooth muscle.
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DOI：
10.1152/ajpcell.2000.278.3.c537
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发表时间：
2000-03
期刊：
影响因子：
--
通讯作者：
A. Rokolya;H. Singer
中科院分区：
文献类型：
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作者：
A. Rokolya;H. Singer
Ca（+）/钙调蛋白依赖性蛋白激酶II（CaM激酶II）参与平滑肌收缩性的调节。本研究的目的是确定：1）在完整动脉平滑肌中，收缩刺激激活CaM激酶II的程度，以及2）CaM激酶II抑制剂（KN-93）对CaM激酶II激活、肌球蛋白调节轻链（MLC（20））磷酸化和力的影响。组胺（1 μ M）和氯化钾去极化激活钙调素激酶II的最大力发展之前的时间过程中，和suprasbasal钙调素激酶II激活持续紧张性收缩。KN-93预处理可抑制CaM激酶II的活化（IC（50）约为1 μ M）。KN-93抑制组胺诱导的张力维持，而在整个时间过程中的早期力发展和MLC（20）磷酸化反应不受影响。KN-93抑制KCl引起的力的发展和维持。KCl诱导的MLC（20）磷酸化的快速增加也被KN-93抑制，而稳态MLC（20）磷酸化反应不受影响。相比之下，佛波醇12，13-二丁酸酯（PDBu）没有激活CaM激酶II和PDBu刺激力的发展是不受KN-93。因此，KN-93似乎靶向对生理刺激作出反应的力维持所必需的步骤，表明CaM激酶II在调节动脉平滑肌的紧张性收缩反应中的作用。蛋白激酶C的药理学活化绕过KN-93敏感步骤。
Ca(+)/calmodulin-dependent protein kinase II (CaM kinase II) has been implicated in the regulation of smooth muscle contractility. The goals of this study were to determine: 1) to what extent CaM kinase II is activated by contractile stimuli in intact arterial smooth muscle, and 2) the effect of a CaM kinase II inhibitor (KN-93) on CaM kinase II activation, phosphorylation of myosin regulatory light chains (MLC(20)), and force. Both histamine (1 microM) and KCl depolarization activated CaM kinase II with a time course preceding maximal force development, and suprabasal CaM kinase II activation was sustained during tonic contractions. CaM kinase II activation was inhibited by KN-93 pretreatment (IC(50) approximately 1 microM). KN-93 inhibited histamine-induced tonic force maintenance, whereas early force development and MLC(20) phosphorylation responses during the entire time course were unaffected. Both force development and maintenance in response to KCl were inhibited by KN-93. Rapid increases in KCl-induced MLC(20) phosphorylation were also inhibited by KN-93, whereas steady-state MLC(20) phosphorylation responses were unaffected. In contrast, phorbol 12,13-dibutyrate (PDBu) did not activate CaM kinase II and PDBu-stimulated force development was unaffected by KN-93. Thus KN-93 appears to target a step(s) essential for force maintenance in response to physiological stimuli, suggesting a role for CaM kinase II in regulating tonic contractile responses in arterial smooth muscle. Pharmacological activation of protein kinase C bypasses the KN-93 sensitive step.