KINETICS OF CONTRACTION INITIATED BY FLASH-PHOTOLYSIS OF CAGED ADENOSINE-TRIPHOSPHATE IN TONIC AND PHASIC SMOOTH MUSCLES
KINETICS OF CONTRACTION INITIATED BY FLASH-PHOTOLYSIS OF CAGED ADENOSINE-TRIPHOSPHATE IN TONIC AND PHASIC SMOOTH MUSCLES
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DOI：
10.1085/jgp.94.4.769
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发表时间：
1989-10-01
影响因子：
3.8
通讯作者：
SOMLYO, AP
中科院分区：
文献类型：
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作者：
HORIUTI, K;SOMLYO, AV;SOMLYO, AP
笼状腺苷三磷酸（ATP），在Ca 2+的存在下，激光闪光光解，被用来检查的时间过程中的等长力的发展从僵硬状态的甘油强直（兔气管）和相位（豚鼠回肠和门静脉）平滑肌。在20 ℃下，ATP从笼状ATP中的光解释放引发了力的产生。C，气管半衰期（t1/2）为5.4 s，相位肌半衰期（t1/2）为1.2-2.2 s。在光解之前，一些肌肉用ATP加冈田酸（肌苷轻链磷酸酶的抑制剂）磷酸化或用ATP γ S硫代磷酸化，以在开启收缩装置之前完全激活调节系统。在这些预磷酸化的肌肉中，在笼状ATP光解后，力的发展比未磷酸化的肌肉更快，但气管的t1/2值（0.8-1.1 s）仍然长于回肠和门静脉肌肉（0.20-0.25 s）。结果表明，无论是收缩机械和调节系统是慢的紧张性比相位平滑肌。每种肌肉类型的力发展的时间过程是S形的，初始延迟（td）为λ。t1/2值的10%。一些可能的化学和机械的延迟的起源进行了讨论。
Laser flash photolysis of caged adenosine triphosphate (ATP), in the presence of Ca2+, was used to examine the time course of isometric force development from rigor states in glycerinated tonic (rabbit trachealis) and phasic (guinea-pig ileum and portal vein) smooth muscles. Photolytic liberation of ATP from caged ATP initiated force development, at 20.degree. C, with half-time (t1/2) of 5.4 s in trachealis and 1.2-2.2 s in the phasic muscles. Prior to photolysis, some muscles were phosphorylated with ATP plus okadaic acid (an inhibitor of myosine light-chain phosphatase) or thiophosphorylated with ATP.gamma.S to fully activate the regulatory system, before turning on the contractile apparatus. In these prephosphorylated muscles, force development, after caged ATP photolysis, was more rapid than in the unphosphorylated muscles, but the t1/2 values for trachealis (0.8-1.1 s) were still longer than for ileum and portal-vein muscles (0.20-0.25 s). The results suggest that both the contractile machinery and the regulatory system are slower in the tonic than in the phasic smooth muscles. The time course of force development for each muscle type was sigmoidal, with an initial delay (td) of .apprx. 10% of the t1/2 value. Some possible chemical and mechanical origins of the delay are discussed.