Nitric oxide-induced decrease in calcium sensitivity of resistance arteries is attributable to activation of the myosin light chain phosphatase and antagonized by the RhoA/Rho kinase pathway
Nitric oxide-induced decrease in calcium sensitivity of resistance arteries is attributable to activation of the myosin light chain phosphatase and antagonized by the RhoA/Rho kinase pathway
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DOI：
10.1161/01.cir.0000074202.19612.8c
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发表时间：
2003-06-24
期刊：
影响因子：
37.8
通讯作者：
Pohl, U
中科院分区：
文献类型：
--
作者：
Bolz, SS;Vogel, L;Pohl, U
背景-NO诱导的阻力动脉（RA）扩张与血管平滑肌细胞Ca（2+）降低无关。我们测试了cGMP依赖的平滑肌肌球蛋白轻链磷酸酶（MLCP）激活导致收缩器的Ca（2+）脱敏是否是潜在的机制，以及它是否可以被RhoA通路拮抗。方法和结果-RA的Ca（2+）敏感性评估为去极化RA中直径变化和[Ca（2+）]（i）之间的关系。（120 mol/L K（+））暴露于逐步增加的Ca（ex）（2+）（0至3 mmol/L）。在应用可溶性鸟苷酸环化酶抑制剂ODQ（1 mumol/L）和MLCP抑制剂calyculin A（120 nmol/L）之前和之后，以及在存在RhoA活化磷脂鞘氨醇-1-磷酸（S1 P，12 nmol/L）的情况下，测定10 mumol/L硝普钠（SNP）对Ca（2+）敏感性的影响。还在对照组和用Rho激酶抑制剂Y27632预处理或用显性负性RhoA突变体（N19 RhoA）转染的RA中研究了SNP诱导的扩张。通过增加Ca（ex）（2+）引起的收缩被SNP显著减弱，然而，这不影响[Ca（2+）]（i）的相关增加。这种NO诱导的衰减被ODQ、calyculin A和S1 P阻断。SNP不能逆转S1 P诱导的RhoA易位，这表明GTdR的激活。N19 RhoA或Y27632对RhoA/Rho激酶的抑制显著增强了SNP诱导的舒张作用。结论- NO通过以cGMP依赖的方式激活MLCP来扩张RA，从而降低收缩器官的表观Ca（2+）敏感性。通过RhoA/Rho激酶途径的MLCP失活拮抗这种Ca（2+）脱敏作用，反过来，可以使用RhoA/Rho激酶抑制剂恢复这种作用。
Background - NO-induced dilations in resistance arteries (RAs) are not associated with decreases in vascular smooth muscle cell Ca(2+). We tested whether a cGMP-dependent activation of the smooth muscle myosin light chain phosphatase (MLCP) resulting in a Ca(2+) desensitization of the contractile apparatus was the underlying mechanism and whether it could be antagonized by the RhoA pathway.Methods and Results-The Ca(2+) sensitivity of RA was assessed as the relation between changes in diameter and [Ca(2+)](i) in depolarized RA (120 mol/L K(+)) exposed to stepwise increases in Ca(ex)(2+) (0 to 3 mmol/L). Effects of 10 mumol/L sodium nitroprusside (SNP) on Ca(2+) sensitivity were determined before and after application of the soluble guanylate cyclase inhibitor ODQ (1 mumol/L) and the MLCP inhibitor calyculin A (120 nmol/L) and in presence of the RhoA-activating phospholipid sphingosine-1-phosphate (S1P, 12 nmol/L). SNP- induced dilations were also studied in controls and in RAs pretreated with the Rho kinase inhibitor Y27632 or transfected with a dominant-negative RhoA mutant (N19RhoA). Constrictions elicited by increasing Ca(ex)(2+) were significantly attenuated by SNP, which, however, left associated increases in [Ca(2+)](i) unaffected. This NO-induced attenuation was blocked by ODQ, calyculin A, and S1P. The S1P-induced translocation of RhoA indicating activation of the GTPase was not reversed by SNP. Inhibition of RhoA/Rho kinase by N19RhoA or Y27632 significantly augmented SNP- induced dilations.Conclusions - NO dilates RA by activating the MLCP in a cGMP-dependent manner, thereby reducing the apparent Ca(2+) sensitivity of the contractile apparatus. MLCP inactivation via the RhoA/Rho kinase pathway antagonizes this Ca(2+)-desensitizing effect that, in turn, can be restored using RhoA/Rho kinase inhibitors.