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。     

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。     

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 smoot hmuscle cell,VSMC）,采用双室培养方式分别观察VSMC缺氧10min和90min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NSC23766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,NSC23766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。     

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     

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。     

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。     

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...     

大电导钙激活钾通道对血管平滑肌的作用

大电导钙激活钾通道(BKCa)是血管平滑肌细胞膜电位的主要离子通道,在血管的舒缩及调节细胞功能方面发挥着重要的作用。BKCa通道的激活可使细胞膜发生超极化,从而抑制电压依赖性钙通道的激活及抑制钙离子内流,导致平滑肌舒张。近年来研究发现,BKCa通道的激活、失活和变异与多种疾病的发病有关,如BKCa对糖尿病、失血性休克、高血压、妊娠期高血压疾病等具有调控作用。     

多巴胺舒张猪冠状动脉及激活冠状动脉平滑肌细胞钾通道

采用血管环实验和膜片钳细胞贴附式技术分别在器官和细胞分子水平观察多巴胺舒张猪冠状动脉作用及对平滑肌细胞大电导型钙激活钾通道(BKCa)的影响 .结果表明多巴胺引起前列腺素 F2α(PGF2α)预收缩动脉环浓度依赖性舒张反应 ,而不引起高 K 预收缩动脉环舒张反应 .表明多巴胺引起的冠状动脉血管舒张反应依赖于 K 生理浓度梯度的存在 ,结果提示钾通道参与了多巴胺的血管舒张反应 .向细胞浴液内灌流多巴胺增强冠状动脉血管平滑肌细胞膜 BKCa通道活性 .用 DA1受体阻断剂 SCH2 3390预处理细胞 ,完全阻断多巴胺的这一作用 ,而用 β受体阻断剂普萘洛尔无影响 .提示多巴胺通过 DA1受体激活 BKCa通道引起 PGF2α预收缩动脉环舒张反应     

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.     

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.     

Opioid receptor antagonists increase [Ca^2＋]i in rat arterial smooth muscle cells in hemorrhagic shock

INTRODUCTION Circulation hypotension induced by hemorrhagicshock is one of the main causes of death after severewounds or trauma. When the hemorrhagic shock hasdeveloped to a decompensatory stage, it is difficult toreverse the hypotension using usual vasoconstrictor,such as norepinephrine. One of the explanations ofhypotension is due to the hyposensitivity of arterialsmooth muscle cells (SMC) to vascular constrictorstimuli[1,2]. Previous studies showed that the vascularhyporesponse was r…     

Sodium pump activity and norepinephrine responsiveness of femoral arterial smooth muscle from DOCA-salt rats

This study investigated the effect of sodium pump activity on vascular smooth muscle responsiveness to norepinephrine (NE) in deoxycorticosterone acetate (DOCA)-salt hypertensive rats. Dose-response curves to NE were generated in normal (5.9 mM), high (10 mM) or 0 mM potassium (K) Krebs physiological solution. Inhibition of the sodium pump (0 mM K) in femoral arterial smooth muscle from control rats resulted in an increased response to NE which was similar to the DOCA-salt rat, while increasing sodium pump activity (10 mM K) in femoral arterial smooth muscle from DOCA-salt rats resulted in a decreased response which was similar to controls. These results show that altering sodium pump activity in vitro by changing extracellular K concentration can affect femoral arterial smooth muscle responsiveness to NE in both control and DOCA-salt rats. Alterations in sodium pump activity observed in vascular smooth muscle from DOCA-salt hypertensive rats may contribute to the increased NE responsiveness and increased vascular resistance seen in this model of hypertension.     

Evidence for the involvement of platelet-derived growth factor in the angiotensin II-induced growth of rat vascular smooth muscle cells

This study examines the possible involvement of endogenous platelet-derived growth factor (PDGF) in the angiotensin II-induced growth of rat aortic smooth muscle cells. In quiescent confluent cells, anti-PDGF-AB neutralizing antibody inhibited angiotensin II-induced DNA synthesis and protein synthesis. PDGF-AA, -AB, and -BB produced concentration-dependent increases in DNA synthesis and protein synthesis. Genistein did not inhibit PDGF-AB-induced [3H]thymidine incorporation and [3H]leucine incorporation. PDGF-AB stimulated mitogen-activated protein (MAP) kinases, and PDGF-induced MAP kinase activation was inhibited by genistein. Angiotensin II induced PDGF-A chain messenger RNA expression, and genistein inhibited angiotensin-induced PDGF gene expression. These findings suggest that endogenous PDGF is, at least in part, involved in angiotensin II-induced cell growth in rat vascular smooth muscle cells. It appears that genistein inhibits angiotensin II-induced DNA synthesis partly by inhibiting PDGF-A gene expression.     

Modulation of Ca2+ channels by opioid receptor antagonists in mesenteric arterial smooth muscle cells of rats in hemorrhagic shock

The effects of hemorrhagic shock on Ba currents ( ) via Ca channels and the regulation of the channels in the vascular hyporesponse stage of hemorrhagic shock by opioid receptor antagonists were examined by using the whole-cell recording of patch-clamp technique in mesenteric arterial smooth muscle cells of rats. The results showed that hemorrhagic shock induced an inhibition of Ca channels in the cells; 10 micro M of naloxone and 100 n of naltrindole, nor-binaltorphimine, and beta-funaltrexamine increased the in the cells of rats in shock. After inhibition of protein kinase C by using 1-(5-isoquindinesulfonyl)-2-methylpiperazine via electrodes, the enhancement of by the antagonists was not observed. These results suggested that the inhibition of Ca channel induced by hemorrhagic shock was mediated by delta-, kappa-, and mu -opioid receptors in the cells and may be partly responsible for vascular hyporesponse. The enhancement of was mediated by activation of protein kinase C and may be responsible for the antagonist-caused improvement in the response of resistance arteries to vasoactive stimulants at the decompensatory stage of hemorrhagic shock.