BKCa compensates impaired coronary vasoreactivity through RhoA/ROCK pathway in hind-limb unweighted rats
BKCa compensates impaired coronary vasoreactivity through RhoA/ROCK pathway in hind-limb unweighted rats
复制标题
BK(Ca) 通过 RhoA/ROCK 通路补偿后肢未体重大鼠受损的冠状血管反应性。
DOI：
10.1096/fj.201901273r
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发表时间：
2019-12-01
期刊：
影响因子：
4.8
通讯作者：
Zhu, Xianyang
中科院分区：
文献类型：
--
作者：
Wu, Yue;Yue, Zhijie;Zhu, Xianyang
先前的研究已经证明了微重力暴露引起的心脏和血管重塑。然而，冠状动脉作为循环心脏的最重要的分支，其在微重力条件下的适应性研究却很少。大电导钙激活钾通道（BKCa）和Ras同源家族成员A（RhoA）/Rho激酶（ROCK）通路在控制血管张力和介导微重力诱导的血管调节中起关键作用。因此，本研究采用4周龄后肢失重（HU）大鼠模拟微重力效应，探讨冠状动脉血管反应性对微重力的适应以及BKCa和RhoA/ROCK通路在其中的作用。右冠状动脉（RCA）收缩采用等长收缩力记录。BKCa和RhoA/ROCK通路的活性和表达通过Western印迹、膜片钳记录和免疫沉淀来检测。HU可显著降低KC 1、5-羟色胺和U-46619引起的RCA收缩反应，但可增加BKCa蛋白表达和电流密度，IBTX抑制HU可进一步降低RCA收缩反应（P < 0.05）。HU可显著增加RhoA和ROCK的表达，增加活性RhoA的表达，增加肌球蛋白轻链（MLC）Ser（19）和MLC磷酸酶靶-1（696）的磷酸化，ROCK抑制剂Y-27632对HU RCA收缩的抑制作用更强（P < 0.05）。BKca开放剂NS 1619增加HU RCA血管收缩，其被RhoA和ROCK抑制剂阻断，类似于IBTX的作用。这些结果表明，HU损害冠状动脉血管收缩，但增强BKca活性作为一种保护机制，避免过度减少冠状动脉血管反应性通过激活RhoA/ROCK途径。
Previous studies have demonstrated cardiac and vascular remodeling induced by microgravity exposure. Yet, as the most important branch of vasculatures circulating the heart, the coronary artery has been seldomly studied about its adaptations under microgravity conditions. Large-conductance Ca2+-activated potassium channel (BKCa) and the Ras homolog family member A (RhoA)/Rho kinase (ROCK) pathway play key roles in control of vascular tone and mediation of microgravity-induced vascular adjustments. Therefore, we investigated the adaptation of coronary vasoreactivity to simulated microgravity and the role of BKCa and the RhoA/ROCK pathway in it. Four-week-old hind-limb unweighted (HU) rats were adopted to simulate effects of microgravity. Right coronary artery (RCA) constriction was measured by isometric force recording. The activity and expression of BKCa and the RhoA/ROCK pathway were examined by Western blot, patch-clamp recordings, and immunoprecipitation. We found HU significantly decreased RCA vasoconstriction to KC1, serotonin, and U-46619, but increased protein expression and current densities of BKCa, inhibition of which by iberiotoxin (IBTX) further decreased RCA vasoconstriction (P < 0.05). Expression of RhoA and ROCK as well as active RhoA and phosphorylation of myosin light chain (MLC) at Ser(19) and MLC phosphatase target-1 at Thr(696) were significantly increased by HU, and ROCK inhibitor Y-27632 exerted greater suppressing effect on HU RCA vasoconstriction than that of control (P < 0.05). BKca opener NS1619 increased HU RCA vasoconstriction, which was blocked by both RhoA and ROCK inhibitor, similar to the effect of IBTX. These results indicate that HU impairs coronary vasoconstriction but enhances BKca activity acting as a protective mechanism avoiding excessive decrease of coronary vasoreactivity through activation of the RhoA/ROCK pathway.