Norepinephrine and GTP-gamma-S increase myofilament Ca2+ sensitivity in alpha-toxin permeabilized arterial smooth muscle.
Norepinephrine and GTP-gamma-S increase myofilament Ca2+ sensitivity in alpha-toxin permeabilized arterial smooth muscle.
复制标题
去甲肾上腺素和 GTP-gamma-S 增加 α 毒素透化动脉平滑肌中肌丝 Ca2+ 的敏感性。
DOI：
10.1016/s0006-291x(88)80303-6
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发表时间：
1988
影响因子：
3.1
通讯作者：
vanBreemen,C
中科院分区：
文献类型：
--
作者：
Nishimura,J;Kolber,M;vanBreemen,C
利用金黄色葡萄球菌产生的一种跨膜造孔外显蛋白α-毒素制备兔肠系膜动脉通透性平滑肌纤维。α-毒素处理后，纤维张力随Ca2+浓度变化（EC50= 890 nM）。但如果没有ATP的加入，它们就不能收缩，这表明ATP是可渗透的。当肌浆网加载5×10−7M Ca2+溶液时，NE在2 mM EGTA 0 M Ca2+溶液中诱导短暂收缩，在5×10−7M Ca2+溶液中诱导短暂且持续的收缩。GTP-γ-S是GTP的不可水解类似物，取代NE产生这些收缩作用。Ca2+与维持张力的关系分析表明，NE和GTP-γ-S分别使肌丝的ec50和160 nM的Ca2+敏感性升高。我们认为NE或GTP-γ-S引起肌丝Ca2+敏感性增加，G蛋白可能参与受体信号转导系统。α-毒素是平滑肌组织渗透离子和小分子而不损害受体和信号转导系统的有效工具。
A new method for preparing permeabilized smooth muscle fibers from rabbit mesenteric artery has been developed using α-toxin, a transmembrane pore-making exo-protein produced by Staphylococcus aureus. After α-toxin treatment the fibers developed tension as a function of Ca2+concentration (EC50= 890 nM). But they could not contract without added ATP, indicating ATP is permeable. When the sarcoplasmic reticulum was loaded with 5×10−7M Ca2+solution, NE induced a transient contraction in 2 mM EGTA 0 M Ca2+solution and a transient and maintained contraction in 5×10−7M Ca2+solution. GTP-γ-S, a non-hydrolyzable analogue of GTP, substituted for NE in producing these contractile effects. The analysis of the relationship between Ca2+and maintained tension revealed that NE and GTP-γ-S cause increases in Ca2+sensitivity of myofilament shifting the EC50to 280 nM and 160 nM, respectively. We conclude that NE or GTP-γ-S causes an increase in myofilament Ca2+sensitivity and that G protein may be involved in receptor signal transduction system. α-Toxin is a useful tool to permeabilize the smooth muscle tissue to ions and small molecules without any damage of receptor and signal transduction system.