Transient myosin phosphorylation at constant Ca2+ during agonist activation of permeabilized arteries.
Transient myosin phosphorylation at constant Ca2+ during agonist activation of permeabilized arteries.
复制标题
在激动剂激活透化动脉期间，恒定 Ca2 下的瞬时肌球蛋白磷酸化。
DOI：
10.1152/ajpcell.1992.263.2.c540
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Moreland,RS
中科院分区：
文献类型：
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作者：
Moreland,S;Nishimura,J;vanBreemen,C;Ahn,HY;Moreland,RS
去甲肾上腺素（NE）加三磷酸鸟苷（GTP）增加α-毒素透化平滑肌中肌丝Ca 2+敏感性。我们使用α-毒素透化的兔肠系膜动脉，以确定在收缩过程中的力，肌球蛋白轻链（MLC）磷酸化，刚度和缩短速度之间的时间关系，在响应单独的Ca 2+和相同的[Ca 2 +]在NE加GTP的存在下。NE加GTP的加入引起了紧张性收缩的显着增加，但仅短暂地升高了MLC磷酸化水平，超过了单独存在Ca 2+时观察到的水平。NE加GTP诱导类似的力和刚度的增加，但缩短速度仅取决于[Ca 2 +]。调节MLC磷酸酶可以解释力和MLC磷酸化的初始增加，但不能维持增强的力，而MLC磷酸化水平下降到类似于单独对Ca 2+的响应值。因此，额外的元素必须参与维持受体和G蛋白依赖性增加肌丝Ca 2+敏感性。
Norepinephrine (NE) plus guanosine triphosphate (GTP) increases myofilament Ca2+ sensitivity in alpha-toxin-permeabilized smooth muscle. We used alpha-toxin-permeabilized rabbit mesenteric arteries to determine the temporal relationships among force, myosin light chain (MLC) phosphorylation, stiffness, and shortening velocity during contractions in response to Ca2+ alone and to the same [Ca2+] in the presence of NE plus GTP. The addition of NE plus GTP caused a marked increase in the tonic contraction but only transiently elevated the level of MLC phosphorylation over that observed in the presence of Ca2+ alone. NE plus GTP induced similar increases in force and stiffness, but shortening velocity depended solely on the [Ca2+]. A regulated MLC phosphatase could explain the initial increase in force and MLC phosphorylation, but not the maintenance of enhanced force while MLC phosphorylation levels fell to values similar to those in response to Ca2+ alone. Therefore, additional elements must be involved in the maintenance of the receptor and G protein-dependent increase in myofilament Ca2+ sensitivity.