ROLE OF SPHINGOSINE KINASE 1 IN REGULATION OF VASCULAR TONE BY ANGIOTENSIN II

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 一些报道暗示鞘氨醇激酶1（SK 1）/鞘氨醇1-磷酸（S1 P）参与细胞内Ca 2+的动员。然而，确切的机制知之甚少。我们使用FLIPR Tetra”测定稳定表达血管紧张素II 1a型（AT 1a）受体的HEK 293细胞以及原代大鼠和小鼠血管平滑肌细胞（VSMC）的细胞内Ca 2+水平的早期观察结果表明，AngII诱导细胞内Ca 2+水平升高的特征模式是，立即达到峰值，随后通过钙池操纵的钙通道（SOC）持续升高Ca 2+。此外，抑制，下调或基因缺失SK 1表达减弱的第一阶段和废除第二阶段的Ca 2+升高。此外，用SK 1抑制剂二甲基鞘氨醇（DMS）预孵育离体兔肾小球的传入小动脉，阻断了持续升高的细胞内Ca 2+和血管紧张素II灌注的血管收缩反应。对野生型和SK 1 KO小鼠进行的体内实验显示，SK 1的缺失逆转了AngII对肾小球滤过率（GFR）的影响。这使我们假设SK 1激活在AngII诱导的细胞内Ca 2+升高中起关键作用，从而调节AngII介导的血管张力和肾微血管血流动力学。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Several reports implicated the involvement of sphingosine kinase 1 (SK1)/sphingosine 1-phosphate (S1P) in the mobilization of intracellular Ca2+. However, the exact mechanism is poorly understood. Our early observation using FLIPR Tetra" to measure the intracellular Ca2+ levels in HEK293 cells stably expressing angiotensin II type 1a (AT1a) receptors and primary rat and murine vascular smooth muscle cells (VSMC), indicates a characteristic pattern of AngII induced increase in intracellular Ca2+ level, an immediate peak followed by a sustained Ca2+ elevation through store operated calcium channels (SOC). Additionally, inhibition, downregulation or genetic deletion of SK1 expression attenuated the first phase and abrogated the second phase of Ca2+ elevation. Moreover, perincubation of the afferent arteriole of the isolated rabbit glomeruli with SK1 inhibitor, dimethylsphingosine (DMS) blocked the sustained elevation of intracellular Ca2+ and vasoconstrictive response of Ang II perfusion. In vivo experiments performed on wild type and SK1KO mice revealed that deletion of SK1 reverses the effect of AngII on glomerular filtration rate (GFR). This has led us to hypothesize that SK1 activation plays a key role in the AngII induced intracellular Ca2+ elevation and thereby regulates AngII-mediated vascular tone and renal microvascular hemodynamic.