Rac对失血性休克大鼠血管反应性的调节作用

目的 探讨Rac在失血性休克大鼠血管反应性调节中的作用。方法 采用SD大鼠复制休克模型,取离体血管环,观察休克早期和晚期血管反应性的变化以及Rac激动剂和特异性抑制剂对休克早期和晚期血管反应性的影响;通过酶消化法培养原代血管平滑肌细胞(vascular smooth muscle cell, VSMC),采用双室培养方式分别观察VSMC缺氧10 min和90 min后VSMC对去甲肾上腺素(norepinephrine, NE)的收缩反应性变化,同时观察Rac活性调节剂对缺氧后VSMC收缩反应性的影响。结果 在休克早期和短暂缺氧后,离体血管环和VSMC对NE收缩反应性均有所升高,Rac的激动剂血小板衍生生长因子(platelet derived growth factor, PDGF)可部分降低休克早期或短暂缺氧后血管反应性,Rac特异性抑制剂NSC 23766可拮抗由PDGF所引起的血管反应性的变化,而在休克晚期或长时间缺氧后,离体血管环和VSMC对NE收缩反应性明显降低,NSC 23766对休克晚期或长时间缺氧所致血管反应性降低有升高作用。结论 休克后血管反应性呈双相变化,休克早期升高,休克晚期降低,Rac参与了休克血管反应性的调节。     

Tie-2介导Ang-1、Ang-2调节大鼠失血性休克血管反应性双相变化的作用研究

目的 观察Tie-2在血管生成素-1(angiopoietin-1, Ang-1)、血管生成素-2(angiopoietin-2, Ang-2)调节失血性休克血管反应性双相变化中的作用。方法 采用离体微血管环张力测定技术和western blot技术,观察失血性休克后不同时间点肠系膜上动脉(superior mesenteric artery,SMA)中Tie-2蛋白表达和磷酸化变化、抑制Tie-2对Ang-1和Ang-2调节缺氧早期和晚期血管反应性作用的影响,以及给予Ang-1和Ang-2后缺氧的血管内皮细胞(vascular endothelial cell, VEC)和血管平滑肌细胞(vascular smooth muscle cell, VSMC)混合细胞中Tie-2蛋白表达和磷酸化变化,并观察抑制Tie-2对缺氧早期和晚期的混合细胞NO含量的影响。结果 (1) 肠系膜上动脉Tie-2蛋白表达和酪氨酸磷酸化在正常时很低,失血性休克后逐渐增高,在休克早期(休克10min),Tie-2蛋白表达变化不大,但酪氨酸磷酸化已明显增高(P<0.01);随着休克时间延长,Tie-2蛋白表达和酪氨酸磷酸化均进一步显著增高(P<0.01)。(2)Tie-2抑制剂可降低缺氧10min的血管高反应性(NE的Emax由13.479mN降低至10.122mN,P<0.05),并显著抑制Ang-1对缺氧10min血管反应性的维持作用(Emax由15.283mN降低至10.253mN,P<0.01);Tie-2抑制剂可改善缺氧4h的血管低反应性(NE的Emax由5.875mN增高至8.003mN,P<0.05),并显著拮抗Ang-2进一步降低缺氧4h血管反应性的作用(Emax由3.444mN增高至7.643mN,P<0.01)。(3)缺氧10min时,降低血管高反应性的Ang-2可降低Tie-2磷酸化,使其由0.0403降低至0.0123(P<0.01);缺氧4h时,恢复血管低反应性的Ang-1可降低Tie-2蛋白表达,使其由0.2276降低至0.0851 (P<0.01),也可以降低Tie-2磷酸化,使其由0.1437降低至0.0359 (P<0.01)。(4) NO含量在缺氧早期显著增高,Ang-2和Tie-2抑制剂显著抑制其增高(P<0.01);缺氧晚期NO含量较正常对照组增高得更为显著,Ang-1和Tie-2抑制剂可抑制其增高(P<0.01)。结论 Ang-1、Ang-2通过Tie-2受体调节大鼠失血性休克血管反应性双相变化。     

蛋白激酶C ε亚型在AVP调节休克血管MLC20磷酸化水平及MLCK/MLCP活性中的作用

目的研究蛋白激酶C（PKC）ε亚型在精氨酸血管加压素（AVP）调节休克血管肌球蛋白轻链（MLC20）磷酸化及缺氧血管平滑肌细胞（VSMC）肌球蛋白轻链激酶（MLCK）和肌球蛋白轻链磷酸酶（MLCP）活性中的作用。方法采用大鼠失血性休克模型和缺氧培养VSMC,观察PKCε亚型在AVP调节失血性休克大鼠肠系膜上动脉（SMA）血管平滑肌MLC20磷酸化水平中的作用,同时检测缺氧VSMC中MLCK和MLCP活性的变化。结果失血性休克后SMA血管平滑肌MLC20磷酸化水平降低,同时缺氧VSMC的MLCP活性明显升高,MLCK活性明显降低;AVP处理可显著升高MLC20磷酸化水平和抑制缺氧VSMC的MLCP活性升高,特异性的PKCε抑制肽可明显拮抗AVP升高MLC20磷酸化、降低MLCP的作用;而AVP和PKCε抑制肽对MLCK活性的变化无明显影响。结论AVP可通过PKCε亚型来发挥改善休克血管反应性的作用,其机制可能是通过抑制MLCP活性、升高MLC20磷酸化水平,进而增强血管平滑肌细胞钙敏感性升高血管反应性。     

血管内皮对狗离体冠状动脉β肾上腺素受体激动剂反应性的影响(英文)

目的:研究内皮细胞对离体冠状动脉β肾上腺素受体激动剂反应性的影响.方法:狗冠状动脉环离体实验,生理记录仪记录血管张力.结果:去甲肾上腺素(NE)和异丙肾上腺素(Iso)引起离体狗冠状动脉剂量依赖性舒张反应,酚妥拉明加强NE的作用.血管去内皮后,对NE和Iso的反应减弱,一氧化氮(NO)合成酶抑制剂N~ω-硝基左旋精氨酸甲酯亦可减弱NE和Iso的作用.结论:β肾上腺素受体激动剂对狗冠状动脉舒张作用部分依赖于内皮.此作用由NO介导.     

精氨酸加压素对失血性休克大鼠血管反应性的影响

目的探讨精氨酸加压素(AVP)对失血性休克大鼠血管反应性的影响,并初步探讨其与Rho激酶的关系。方法在体实验,观察大鼠失血性休克后AVP对去甲肾上腺素(NE)升压反应的影响;离体实验,测定失血性休克大鼠肠系膜上动脉(SMA)环对NE的收缩反应和去极化状态下(120mmol·L-1K+)对Ca2+的收缩反应,反映其对缩血管物质和钙的反应性。结果失血性休克(4kPa,2h)后大鼠对NE的升压反应显著下降。AVP0.1和0.4U·kg-1,iv,随后再将AVP溶于3倍失血量的复方氯化钠溶液分别以0.01和0.04U·kg-1·min-1的速度于30min内用输液泵输注,3～4h后可使NE的升压反应恢复至正常组水平。失血性休克后SMA对NE和钙的反应性显著下降,对NE和Ca2+的收缩反应量效曲线明显右移,最大反应(Emax)降低;加入NE和Ca2+前分别用0.5和5nmol·L-1AVP孵育10min可使NE和Ca2+的收缩反应量效曲线明显左移,Emax显著增高。Rho激酶拮抗剂HA1077预处理可部分取消AVP所致的Ca2+Emax变化,使Emax回降。结论AVP能升高失血性休克大鼠血管对NE的敏感性及反应效能和血管平滑肌对钙的反应效能。     

蛋白激酶C ε亚型在AVP调节休克血管MLC20磷酸化水平及MLCK/MLCP活性中的作用

目的 研究蛋白激酶C(PKC) ε亚型在精氨酸血管加压素(AVP)调节休克血管肌球蛋白轻链(MLC₂₀)磷酸化及缺氧血管平滑肌细胞(VSMC)肌球蛋白轻链激酶(MLCK)和肌球蛋白轻链磷酸酶(MLCP)活性中的作用。方法 采用大鼠失血性休克模型和缺氧培养VSMC,观察PKC ε亚型在AVP调节失血性休克大鼠肠系膜上动脉(SMA)血管平滑肌MLC20磷酸化水平中的作用,同时检测缺氧VSMC中MLCK和MLCP活性的变化。结果 失血性休克后SMA血管平滑肌MLC₂₀磷酸化水平降低,同时缺氧VSMC的MLCP活性明显升高,MLCK活性明显降低;AVP处理可显著升高MLC₂₀磷酸化水平和抑制缺氧VSMC的MLCP活性升高,特异性的PKC ε抑制肽可明显拮抗AVP升高MLC₂₀磷酸化、降低MLCP的作用;而AVP和PKC ε抑制肽对MLCK活性的变化无明显影响。结论 AVP可通过PKC ε亚型来发挥改善休克血管反应性的作用,其机制可能是通过抑制MLCP活性、升高MLC₂₀磷酸化水平,进而增强血管平滑肌细胞钙敏感性升高血管反应性。     

血管紧张素Ⅱ通过激活小G蛋白Rac1上调Fgf13促进大鼠心脏成纤维细胞的增殖迁移

目的 研究AngⅡ激活Rac1后,其下游促进心肌纤维化的新机制。方法 (1)构建Ad-Rac1、Ad-Rac1-V12腺病毒,转染心房成纤维细胞(atrial fibroblasts,AFs),收集样本通过Western Blot法检测Fgf13的表达差异;(2)用AngⅡ刺激AFs,并加入Rac1特异性抑制剂NSC23766,检测Fgf13表达变化;(3)培养大鼠原代AFs并分三组进行处理:Ad-Vector组、Ad-Rac1-V12组及Ad-Rac1-V12+Si-Fgf13组,检测各组AFs的Ⅰ型胶原蛋白(CollagenⅠ)、α-SMA的表达变化;(4)CCK-8及细胞划痕实验检测各组细胞增殖及迁移能力。结果 AngⅡ刺激后活化型Rac1表达显著升高(P 0.05)。AFs转染腺病毒后发现,且相较于Ad-Rac1组,Ad-Rac1-V12组Fgf13、CollagenⅠ及α-SMA表达均显著上调(P 0.05)。而使用Rac1特异性抑制剂NSC23766后,Fgf13表达量均显著下降(P 0.05)。此外,使用小干扰技术抑制Fgf13表达后,发现与Ad-Rac1-V12组相比,Ad-Rac1-V12+Si-Fgf13组CollagenⅠ、α-SMA表达降低,AFs增殖、迁移能力下降(P 0.05)。结论 血管紧张素Ⅱ可通过激活小G蛋白Rac1上调Fgf13的表达,进而促进心房成纤维细胞增殖迁移及纤维化相关蛋白的表达。     

三羟异黄酮对失血性休克大鼠肠系膜上动脉收缩反应性的影响

目的研究三羟异黄酮(genistein,GST)对失血性休克大鼠肠系膜上动脉收缩反应性的影响及其可能机制。方法建立大鼠失血性休克(3.9kPa,2h)模型。采用离体血管环张力测定实验,观察三羟异黄酮及酪氨酸蛋白磷酸酶抑制剂钒酸钠(sodiumorthovannadate,Na3VO4)对休克大鼠肠系膜上动脉血管收缩反应性的影响;采用细胞贴附式膜片钳记录技术,观察三羟异黄酮及钒酸钠对休克大鼠肠系膜上动脉平滑肌细胞大电导钙激活钾通道(largeconductancecalciumactivatedpotassiumchannel,BKCa)活动的影响。结果失血性休克导致大鼠肠系膜上动脉对去甲肾上腺素(noradrenine,NE)的收缩反应性降低,三羟异黄酮可在一定的剂量范围内明显改善失血性休克引起的血管低反应性;钒酸钠则可引起休克血管收缩反应性的进一步降低,且该作用可被0.1mmol·L-1TEA部分阻断;进一步的研究显示,失血性休克可引起大鼠肠系膜上动脉血管平滑肌细胞BKCa通道活动的增强,三羟异黄酮可抑制休克血管平滑肌细胞BKCa通道活动,且该作用可被钒酸钠逆转。结论三羟异黄酮可通过干预由PTK介导的酪氨酸蛋白磷酸化,防止失血性休克血管平滑肌细胞BKCa通道活动的增强,从而有效恢复失血性休克大鼠肠系膜上动脉对NE的收缩反应性。     

粉防己碱对肾血管性高血压大鼠阻力血管反应性的影响

目的　探讨肾血管性高血压 (RH)大鼠阻力血管重构时功能变化特点 ,分析粉防己碱的影响与机制。方法　两肾一夹法制备RH大鼠模型 ,观察肠系膜动脉床和尾动脉对收缩和舒张刺激的反应性。结果　RH大鼠肠系膜动脉和尾动脉对去甲肾上腺素 (NE)诱导的收缩反应性增高 ,最大收缩值增大 ;对乙酰胆碱和硝普钠引起的血管舒张反应性降低 ;对鸟苷酸环化酶 (GC)抑制剂敏感性下降。粉防己碱降低肠系膜动脉的静息阻力和NE诱导的阻力升高幅度 ,改善去内皮后或GC抑制后血管压力及管壁张力。结论　RH大鼠阻力血管对收缩刺激反应性增高 ,对内皮依赖及非内皮依赖性的舒张刺激反应性降低 ;粉防己碱可通过保护内皮和维护细胞GC活性而有效逆转阻力血管功能异常     

三味檀香水提液对大鼠离体主动脉环的作用

目的探讨三味檀香水提液(ESWTX)对离体大鼠主动脉环的舒张作用。方法采用离体大鼠主动脉环张力记录法,观察ESWTX对去甲肾上腺素(NE)、KCl引起的血管平滑肌收缩的影响。结果ESWTX能使NE、KCl收缩血管平滑肌的最大反应下降,作用机制与维拉帕米相似;对NE、KCl收缩达峰值的离体大鼠主动脉环有舒张作用;对NE引起的依赖于细胞内钙收缩有明显的抑制作用,而对外钙收缩的抑制作用比较弱。结论ESWTX的作用类似于维拉帕米,具有舒张血管平滑肌的作用,其机制可能与拮抗钙离子有关。     

Regulatory effect of Rac1 on vascular reactivity after hemorrhagic shock in rats

We used isolated superior mesenteric arteries (SMAs) from hemorrhagic-shock rats and hypoxia-treated vascular smooth muscle cells (VSMCs; mimicking the shock state) to observe the effects of platelet-derived growth factor (PDGF; Rac1 stimulator) and NSC23766 (Rac1 antagonist) on vascular reactivity and the relationship with the Rho kinase-myosin light-chain phosphatase (MLCP) and p21-activated kinase (PAK)-myosin light-chain kinase (MLCK) signal pathway. The results indicated that the contractile responses of the SMAs and VSMCs were significantly increased at early shock or after transient hypoxia. NSC23766 (Rac1 antagonist) further increased, whereas PDGF (Rac1 stimulator) decreased the contractile responses of SMAs and VSMCs. In the late period of shock or prolonged hypoxia, the contractile responses of SMAs and VSMCs were significantly decreased; NSC23766 increased (whereas PDGF further decreased) the contractile response of the SMAs and VSMCs. Activation of Rac1 with PDGF significantly increased the activity of PAK and MLCP, and decreased Rho kinase and MLCK activity and 20-kDa myosin light-chain phosphorylation in VSMCs. The PAK inhibitor PAK-18 significantly antagonized the PDGF-induced decrease in MLCK activity, whereas the Rho kinase antagonist Y-27632 further enforced the PDGF-induced increase in MLCP activity. Simple fluid resuscitation did not improve but in combination with NSC23766 significantly improved vascular reactivity and animal survival at 24 hours. This suggested that Rac1 has an inhibitory effect on vasoreactivity after shock. Rac1-mediated regulation of vascular reactivity is mainly through activation of PAK, inhibition of MLCK and inhibition of Rho kinase, unpack the inhibition of Rho kinase to MLCP. Rac1 may be a potential target to treat vascular hyporeactivity in many critical conditions.     

Effects of MCI-154 on vascular reactivity and its mechanisms after hemorrhagic shock in rats

The objectives of this study were to investigate the effects of 6-[4-(4'-pyridylamino)phenyl]-4,5-dihydro-3(2H)-pyridazinone hydrochloride trihydrate (MCI-154), a newly developed cardiotonic agent, on vascular reactivity and contractile responses to extracellular Ca2+ ([Ca2+]o) after hemorrhagic shock and primarily explore its mechanism. In vivo, the effects of MCI-154 (0.1, 0.5, 1.0, and 2.0 mg/kg) on the pressor effect of norepinephrine (NE) in rats subjected to hemorrhagic shock (30 mm Hg for 2 h) were observed and in vitro, the effects of MCI-154 (10(-7), 10(-6), 10(-5), 10(-4) mol/L) on vascular reactivity and contractile responses to [Ca2+]o of superior mesenteric artery (SMA) from hemorrhagic shock rats and its relationship to Rho-kinase, protein kinase C (PKC), and protein kinase G (PKG) were observed. The results showed that the NE-induced pressor response after hemorrhagic shock was significantly decreased (P<0.01), and MCI-154 made it decrease further. In vitro, MCI-154 further decreased the contractile responses of SMA to NE and Ca2+ after hemorrhagic shock as compared with untreated hemorrhagic shock group (P<0.01). Angiotensin II (Ang II), with Rho-kinase stimulating action, and PMA, a PKC agonist increased the contractile responses to [Ca2+]o of SMA after hemorrhagic shock. MCI-154 (10(-5) mol/L) partly inhibited Ang II and PMA-induced increase of the contractile responses to [Ca2+]o of SMA (P<0.01). KT-5823, the PKG antagonist, antagonized MCI-154-induced decrease of the contractile responses to [Ca2+]o. Taken together, these results suggested that the vascular reactivity and contractile responses to [Ca2+]o of vascular smooth muscle after hemorrhagic shock were significantly decreased. MCI-154 worsened hemorrhagic shock-induced vascular hyporeactivity and the decrease of contractile responses to [Ca2+]o. These effects were possibly regulated by Rho-kinase, PKC, and PKG, but this needs further confirmation.     

肌内皮缝隙连接在失血性休克大鼠内皮依赖和非内皮依赖的血管舒/缩功能调节中的作用

目的 研究肌内皮缝隙连接(myo-endothelial gap junction,MEGJ)通道在失血性休克大鼠肠系膜上动脉血管(SMA)的内皮依赖和非内皮依赖的血管收缩/舒张功能调节中的作用.方法 利用在体血管管径测定技术,观察MEGJ的阻断剂18α-甘草次酸(18α-GA)对非内皮依赖的血管收缩剂去甲肾上腺素(N...     

Ryanodine receptor 2 contributes to hemorrhagic shock-induced bi-phasic vascular reactivity in rats

Aim:

Ryanodine receptor 2 (RyR2) is a critical component of intracellular Ca²⁺ signaling in vascular smooth muscle cells (VSMCs). The aim of this study was to investigate the role of RyR2 in abnormal vascular reactivity after hemorrhagic shock in rats.

Methods:

SD rats were hemorrhaged and maintained mean arterial pressure (MAP) at 40 mmHg for 30 min or 2 h, and then superior mesenteric arteries (SMA) rings were prepared to measure the vascular reactivity. In other experiments, SMA rings of normal rats and rat VSMCs were exposed to a hypoxic medium for 10 min or 3 h. SMA rings of normal rats and VSMCs were transfected with siRNA against RyR2. Intracellular Ca²⁺ release in VSMCs was assessed using Fura-2/AM.

Results:

The vascular reactivity of the SMA rings from hemorrhagic rats was significantly increased in the early stage (30 min), but decreased in the late stage (2 h) of hemorrhagic shock. Similar results were observed in the SMA rings exposed to hypoxia for 10 min or 3 h. The enhanced vascular reactivity of the SMA rings exposed to hypoxia for 10 min was partly attenuated by transfection with RyR2 siRNA, whereas the blunted vascular reactivity of the SMA rings exposed to hypoxia for 3 h was partly restored by transfection with RyR2 siRNA. Treatment with the RyR agonist caffeine (1 mmol/L) significantly increased Ca²⁺ release in VSMCs exposed to hypoxia for 10 min or 3 h, which was partially antagonized by transfection with RyR2 siRNA.

Conclusion:

RyR2-mediated Ca²⁺ release contributes to the development of bi-phasic vascular reactivity induced by hemorrhagic shock or hypoxia.     

Beneficial effect of arginine vasopressin on hemorrhagic shock through improving the vascular reactivity

The vascular reactivity and calcium sensitivity were decreased following hemorrhagic shock. Arginine vasopressin (AVP) was beneficial to endotoxic, infectious/spetic and hemorrhagic shock. Our previous studies found that Rho kinase played an important role in the occurrence of calcium desensitization following shock. It was reported that AVP was with stimulation effect of Rho kinase. So we hypothesized that AVP might have beneficial effect on shock via activation of Rho kinase to regulate the calcium sensitivity and vascular reactivity. Hemorrhagic shock (40 mmHg for 2 h) Wistar rats in vivo were adopted to observe the effects of small dose of AVP on hemodynamics, 24-h survival rate, the pressor effect of norepinephrine (NE) and the contractility of superior mesenteric artery (SMA). Isolated SMAs from hemorrhagic shock rats were adopted to observe the effects of AVP on vascular reactivity and calcium sensitivity and its relationship to Rho kinase with an isolated organ perfusion system. The results show that AVP at the concentration of 0.1 U/kg and 0.4 U/kg significantly improved the hemodynamic parameters and the 24-h survival rate of hemorrhagic shock rats. Meanwhile, these dosages of AVP significantly increased the pressor effect of NE and the contractile response of SMA to NE. Y-27632 (3 μg/kg), a Rho kinase specific inhibitor, abolished the beneficial effects of AVP. In vitro, the calcium sensitivity and vascular reactivity of SMA to calcium and NE were significantly decreased following hemorrhagic shock. AVP at the concentration of 0.5 nmol/L and 5 nmol/L significantly increased the calcium sensitivity and vascular reactivity. These effects of AVP were abolished by Y-27632 (10 μmol/L). Taken together, the results suggest that AVP at 0.1 U/kg and 0.4 U/kg is beneficial to hemorrhagic shock by improving the vascular reactivity, which involves activation of Rho kinase.     

鱼腥草注射液过敏及类过敏实验研究

目的评价鱼腥草注射液及其辅料吐温80（Tween-80）静脉给药的致敏性。方法采用Beagle犬类过敏及过敏实验,观察给药后动物行为变化和检测血浆中组胺、IgE、IgM、IgG的含量。结果含有Tween-80的鱼腥草注射液及Tween-80组动物给药后出现显著的行为异常,血浆组胺升高,而IgE变化不规律,IgG、IgM则无明显改变。结论鱼腥草注射液中导致犬严重类过敏反应与Tween-80有关。建议Beagle犬的过敏及类过敏试验,应作为中药注射液致敏试验的必做实验,行为异常及血浆中组胺为主要的判定指标,IgE作为辅助判定指标。     

The Role of Rac1 on Carbachol‐induced Contractile Activity in Detrusor Smooth Muscle from Streptozotocin‐induced Diabetic Rats

This study was designed to determine the role of the small GTPase Rac1 on carbachol‐induced contractile activity in detrusor smooth muscle using small inhibitor NSC 23766 in diabetic rats. Rac1 expression in bladder tissue was also evaluated. In the streptozotocin (STZ)‐induced diabetic rat model, three study groups were composed of control, diabetic and insulin‐treated diabetic subjects. The detrusor muscle strips were suspended in organ baths at the end of 8–12 weeks after STZ injection. Carbachol (CCh) (10^?9–10^?4 M) concentration–response curves were obtained both in the absence and in the presence of Rac1 inhibitor NSC 23766 (0.1, 1 and 10 μM). Diabetes‐related histopathological changes and Rac1 expressions were assessed by haematoxylin and eosin staining and immunohistochemical staining, respectively. CCh caused dose‐dependent contractile responses in all the study groups. Rac1 inhibitor NSC 23766 inhibited CCh‐induced contractile responses in all groups, but this inhibition seen in both diabetes groups was greater than in the control group. Histological examination revealed an increased bladder wall thickness both in the diabetes and in the insulin‐treated diabetes groups compared to the control group. In immunohistochemical staining, expression of Rac1 was observed to be increased in all layers of bladder in both diabetic groups compared to the control group. In the diabetic bladders, increased expression of Rac1 and considerable inhibition of CCh‐induced responses in the presence of NSC 23766 compared to those of the control group may indicate a specific role of Rac1 in diabetes‐related bladder dysfunction, especially associated with cholinergic mediated detrusor overactivity.