重症休克时平滑肌细胞内的钙动力学变化

使用荧光比率方法研究血管平滑肌细胞钙动力学变化在重症休克血管反应性降低中的作用．复制SD大鼠失血性休克模型,分离肠系膜细动脉血管平滑肌(ASMC)．使用荧光探针Fluo-3／AM、FuraRed双标记比率方法结合激光扫描共聚焦显微成像技术测定单个平滑肌细胞钙动力学变化,观察ATP敏感钾通道(KATP)特异性阻滞剂优降糖对血管反应性和钙动力学影响、实验结果发现休克后2h(失代偿期),血管反应性明显降低,norepinephrine作用带来的平滑肌细胞内钙离子浓度升高的程度明显减弱;加入优降糖可明显提高NE对平滑肌细胞内钙离子的升高作用,改善细动脉对NE的反应性．带来血管反应性部分恢复．     

Role of oxygen-derived free radicals on rat splanchnic eicosanoid production during acute hemorrhage.

The effect of superoxide dismutase (SOD), an oxygen-derived free radical scavenger, on rat splanchnic eicosanoid synthesis was examined following hemorrhagic shock. Anesthetized male rats were hemorrhaged to 30 mm Hg for 30 minutes (Shock), killed, or treated with the shed blood (Shock plus reperfusion). The Shock plus reperfusion group was treated with saline vehicle or SOD (2500, 5000, 7500, 10,000 or 15,000 U/Kg, i.v.) 15 minutes prior to the reperfusion of the shed blood. The superior mesenteric artery was removed in continuity with the end organ intestine (SV+SI) and perfused in vitro with oxygenated Krebs-Henseleit buffer (3 ml/min at 37 degrees C). Venous effluent was measured for basal release of 6-keto-PGF1 alpha, PGE2 and thromboxane B2 at 15, 30, 60 and 90 minutes of perfusion. The SV+SI compensated for acute shock by increased release of 6-keto-PGF1 alpha (300%) (and not PGE2 or thromboxane B2) which was abolished by reperfusion of the shed blood following shock. Prior treatment of the Shock plus reperfusion group with 7500 U/Kg or more of SOD restored the increased release of SV+SI 6-keto-PGF1 alpha found following shock alone (p less than 0.05). These data provided indirect evidence that ODFRs contributed to endogenous SV+SI regulation of PGI2 synthesis and release during hemorrhagic shock and reperfusion of shed blood.     

Sensitivity to endotoxin in rabbits is increased after hemorrhagic shock.

The immunoinflammatory response following trauma and hemorrhage may predispose to the development of sepsis and multiple-organ failure syndrome. Cardiac output (CO), arterial pressure, arterial PO2, and pulmonary permeability index were measured. We examined the sensitivity of rabbits to infusions of lipopolysaccharide (LPS) after hemorrhagic shock. Shock was produced by reducing CO to 40% of baseline for 90 min, followed by resuscitation with shed blood and then with lactated Ringer solution to maintain CO near baseline. Animals were assigned to three groups: 1) hemorrhagic shock only, 2) LPS only, and 3) hemorrhagic shock + LPS. Groups 1 and 3 were subjected to hemorrhagic shock on day 1. Escherichia coli LPS was infused (1.0 microgram/kg i.v.) into groups 2 and 3 on day 2. Fluid resuscitation with lactated Ringer solution was continued in an effort to maintain CO at baseline. Five hours after LPS infusion, 125I-albumin was injected intravenously, and rabbits were killed 1 h later for measurement of pulmonary permeability index. LPS infusion after shock (group 3) caused significant decreases in CO, arterial pressure, and PO2 and an increase in pulmonary permeability. These changes were not seen in the groups 1 and 2. We conclude that hemorrhagic shock and resuscitation result in a proinflammatory state, leading to increased sensitivity to subsequent exposure to LPS.     

内毒素移位在肠淋巴再灌注加剧SMAO休克大鼠多器官损伤中的作用

目的:探讨肠源性内毒素移位在肠淋巴再灌注(MLR)加剧肠系膜上动脉闭塞性(SMAO)休克多器官损伤中的作用与机制。方法:24只Wistar大鼠随机分为4组(n=6):假手术组(Sham,仅麻醉与手术)、MLR组(夹闭肠系膜淋巴管1 h,再灌注2 h)、SMAO组(夹闭肠系膜上动脉1 h,再灌注2 h)和SMAO+MLR组(同时夹闭肠系膜淋巴管和肠系膜上动脉1 h,再灌注2 h)。再灌注2 h后,腹主动脉取血,制备血浆;留取固定位置的肝、肾、心肌、肺组织,制备组织匀浆。应用鲎试剂动态浊度法检测血浆以及各组织匀浆内毒素(ET)含量;应用酶联免疫方法检测各器官组织匀浆脂多糖结合蛋白(LBP)、脂多糖受体(CD14)和肿瘤坏死因子(TNF-α)水平。结果:Sham组和MLR组各指标均无统计学差异;SMAO组及SMAO+MLR组的血浆、肝、肾、心肌、肺组织匀浆的ET含量均显著高于Sham组和MLR组,且SMAO+MLR组血浆及各组织匀浆的ET水平均显著高于SMAO组;SMAO组及SMAO+MLR组肝、肾、心肌、肺组织匀浆CD14、LBP和TNF-α水平显著高于Sham组及MLR组,且SMAO+MLR组各指标均高于SMAO组。结论:MLR加剧SMAO休克多器官损伤的作用机制与ET经过肠淋巴途径移位、激活内毒素增敏系统LBP/CD14、促进炎症反应有关。     

淋巴液的抗休克作用

目的和方法：应用显微电视录象设备和活体大鼠肠系膜微循环观察技术,观察胸导管淋巴液对重症失血性休克大鼠血压和微循环障碍的影响,以探讨淋巴液的抗休克作用及其机制。结果：淋巴液治疗组大鼠存活时间（７０３ｈ）显著高于白蛋白对照组（２０５ｈ）。治疗组输入胸导管淋巴液后血压显著回升,血液流态改善,有效地解除肠系膜细动、静脉和微淋巴管（ＭＬ）静态口径的病理性收缩,ＭＬ收缩分数、总收缩活性指数及淋巴管动力学指数恢复正常,而白蛋白对照组的微血管口径及三个ＭＬ收缩性指数仍处于休克时水平,且明显低于治疗组（Ｐ＜０．０１）。结论：淋巴液具有良好的抗休克作用,其机制可能与显著改善休克时的微循环障碍和提升血压有关     

肠淋巴液引流对失血性休克小鼠心肌组织ACE/ACE2的作用

目的：观察失血性休克后小鼠心肌组织血管紧张素转换酶（ACE）/ACE2平衡的变化及肠淋巴液引流（PHSML）的作用。方法：BALB/c雄性小鼠24只,随机分为对照组、假手术组、休克组、休克+引流组（n=6）。建立失血性休克模型,行液体复苏;休克+引流组液体复苏后,引流肠淋巴液。在液体复苏后6 h或假手术组相应时间点、对照组于麻醉后,留取心肌组织,qRT-PCR法检测ACE、ACE2、血管紧张素Ⅱ （Ang Ⅱ）1型受体（AT1R）、Mas相关G蛋白偶联受体（Mas1R）的mRNA表达,ELISA方法检测Ang Ⅱ和Ang （1-7）含量。结果：休克组小鼠心肌组织ACE与AT1R mRNA表达、Ang Ⅱ水平均显著高于对照组与假手术组,ACE2与Mas1R mRNA表达显著低于对照组与假手术组、Ang （1-7）含量显著低于对照组,ACE/ACE2、Ang Ⅱ/Ang （1-7）、AT1R/Mas1R显著高于对照组与假手术组;PHSML引流显著抑制了失血性休克对这些指标的作用。结论：失血性休克上调心肌ACE-Ang Ⅱ-AT1R轴、下调ACE2-Ang （1-7）-Mas1R轴表达,引起ACE/ACE2失衡;PHSML引流下调ACE-Ang Ⅱ-AT1R轴、上调ACE2-Ang （1-7）-Mas1R轴表达,在一定程度上维持了ACE/ACE2平衡。     

肠淋巴液引流对失血性休克大鼠红细胞流变性的影响

目的:观察肠淋巴液引流对失血性休克大鼠红细胞流变性指标以及血液黏度的作用。方法:Wistar雄性大鼠均分为假休克组、休克组(复制失血性休克模型)、引流组(复制失血性休克模型,自低血压1 h引流休克肠淋巴液)。在低血压3 h或相应时间,经腹主动脉取血,检测红细胞参数、红细胞电泳、红细胞沉降率(ESR)以及血液黏度,计算红细胞聚集指数、红细胞变形指数。结果:与假休克组比较,休克组红细胞数量、红细胞比积(HCT)、血红蛋白(Hb)、平均红细胞血红蛋白浓度(MCHC)、红细胞电泳率与迁移率、红细胞变形指数、全血黏度、全血低切与高切相对黏度和还原黏度显著降低,休克组平均红细胞体积、红细胞电泳时间、ESR、血沉方程K值与校正K值、红细胞聚集性指数、血浆黏度显著升高;引流组MCHC、红细胞电泳率与迁移率、全血黏度、全血低切与高切还原黏度均显著降低,引流组红细胞体积分布宽度(RDW-SD)显著增加。同时,引流组HCT、RDW-SD、红细胞变形指数、全血黏度、全血低切与高切相对黏度显著高于休克组;ESR、血沉方程K值与校正K值、红细胞聚集性指数、血浆黏度显著低于休克组。结论:休克肠淋巴液引流可改善失血性休克大鼠红细胞流变行为,从而改善血液流变性。     

灵光注射液对失血性休克大鼠胃肠粘膜的保护作用

目的　观察灵光注射液 (复方樟柳碱 )对失血性休克再灌注大鼠胃肠粘膜损伤的影响。方法　将 5 6只雄性Wistar大鼠随机分 4组 ,分别设为假休克组 (8只 )、模型组 (16只 )、灵光注射液低剂量组 (16只 )和高剂量组(16只 ) ,除假休克组外 ,大鼠均经历 4kPa ,70min的失血性休克 ,在休克复苏后 6h和 12h各组分别处死半数动物 ,观察大鼠肠道菌移位情况、病理组织学和超微结构变化。结果　灵光注射液对大鼠失血性休克再灌注引起的肠道细菌移位和胃肠粘膜形态损伤有明显的保护作用 ,其治疗机制可能与改善微循环、清除氧自由基作用有关     

Mechanism of enhanced calcium sensitivity and alpha 2-AR vasoreactivity in chronic NOS inhibition hypertension

PKC augments calcium sensitivity in spontaneously hypertensive rats and contributes to alpha(2)-adrenergic receptor (AR) contraction in rabbit saphenous vein. We showed previously that denuded aortic rings from N(omega)-nitro-l-arginine-treated hypertensive rats (LHR) contract more to CaCl(2) and to the alpha(2)-AR agonist UK-14304 than do rings from normotensive rats (NR). We hypothesized that enhanced PKC activity or a change in PKC isoform contributes to augmented calcium sensitivity and enhanced alpha(2)-AR contraction in LHR aorta. Current studies demonstrate that non-isoform-specific PKC inhibitors reduced UK-14304 contraction in both NR and LHR aorta. However, the calcium-dependent PKC inhibitor G?-6976 only attenuated contraction in LHR aorta. Additionally, UK-14304 translocated PKC-delta to the membrane in NR aorta, whereas PKC-alpha was translocated to the membrane in LHR aorta. Finally, in ionomycin-permeabilized aorta G?-6976 eliminated enhanced basal and augmented alpha(2)-AR-stimulated calcium sensitivity in LHR aorta but did not affect NR contraction. Together, these data suggest that PKC-alpha contributes to augmented calcium sensitivity and alpha(2)-AR reactivity after chronic nitric oxide synthase inhibition hypertension.     

Effect of heating on vascular reactivity in rat mesenteric arteries

Vasoconstrictionin the viscera is one of the primary cardiovascular adjustments toheating. Local temperature can influence vascular responsiveness tocatecholamines and sympathetic nerve activity. Therefore, wehypothesized that heating would alter vascular reactivity in ratmesenteric arteries. Concentration-response curves to norepinephrine,phenylephrine, potassium chloride (KCl), calcium, acetylcholine, andsodium nitroprusside were obtained in vascular ring segments from ratmesenteric arteries at 37 and 41°C. In some rings, basal tensionincreased slightly during heating. Heating to 41°C did not alterthe contractile responses to norepinephrine in endothelium-intact or-denuded rings but augmented the responses to KCl and calcium inendothelium-intact rings. The potentiating effect of heating on theresponses to KCl and calcium was eliminated after endothelium removal.In contrast, the relaxant responses to acetylcholine and sodiumnitroprusside were significantly attenuated at 41°C. Collectively,these results demonstrate that heating alters vascular reactivity inrat mesenteric arteries. Furthermore, these data imply that heatingreduces the ability of vascular smooth muscle to relax, possibly due toa decrease in sensitivity to nitric oxide.

     

Lymphocyte modulation with FTY720 improves hemorrhagic shock survival in swine

The inflammatory response to severe traumatic injury results in significant morbidity and mortality. Lymphocytes have recently been identified as critical mediators of the early innate immune response to ischemia-reperfusion injury. Experimental manipulation of lymphocytes following hemorrhagic shock may prevent secondary immunologic injury in surgical and trauma patients. The objective of this study is to evaluate the lymphocyte sequestration agent FTY720 as an immunomodulator following experimental hemorrhagic shock in a swine liver injury model. Yorkshire swine were anesthetized and underwent a grade III liver injury with uncontrolled hemorrhage to induce hemorrhagic shock. Experimental groups were treated with a lymphocyte sequestration agent, FTY720, (n = 9) and compared to a vehicle control group (n = 9). Animals were observed over a 3 day survival period after hemorrhage. Circulating total leukocyte and neutrophil counts were measured. Central lymphocytes were evaluated with mesenteric lymph node and spleen immunohistochemistry (IHC) staining for CD3. Lung tissue infiltrating neutrophils were analyzed with myeloperoxidase (MPO) IHC staining. Relevant immune-related gene expression from liver tissue was quantified using RT-PCR. The overall survival was 22.2% in the vehicle control and 66.7% in the FTY720 groups (p = 0.081), and reperfusion survival (period after hemorrhage) was 25% in the vehicle control and 75% in the FTY720 groups (p = 0.047). CD3(+) lymphocytes were significantly increased in mesenteric lymph nodes and spleen in the FTY720 group compared to vehicle control, indicating central lymphocyte sequestration. Lymphocyte disruption significantly decreased circulating and lung tissue infiltrating neutrophils, and decreased expression of liver immune-related gene expression in the FTY720 treated group. There were no observed infectious or wound healing complications. Lymphocyte sequestration with FTY720 improves survival in experimental hemorrhagic shock using a porcine liver injury model. These results support a novel and clinically relevant lymphocyte immunomodulation strategy to ameliorate secondary immune injury in hemorrhagic shock.     

Endothelin-1 Increases Arachidonic Acid Release in C6 Glioma Cells Through a Potassium-Modulated Influx of Calcium

Abstract: Endothelin-1 (Et-1) but not a range of other receptor agonists stimulated the release of arachidonic acid (AA) in C6 glioma. Et-1 activation was concentration dependent and was inhibited by chelation of extracellular calcium. The calcium ionophores A23187 and ionomycin could also stimulate release of AA. Et-1 caused an early increase in intracellular Ca²⁺ concentration ([Ca²⁺]_i) followed by a sustained but lower plateau level. The sensitivity of the response to quinacrine, its dependence on Ca²⁺, and the demonstration of an increase in phospholipase A₂ (PLA₂) activity that was insensitive to dithiothreitol suggested that the release of AA was due to activation of cytosolic PLA₂ in the cells. Staurosporine, a protein kinase C (PKC) inhibitor, had no effect on Et-1-induced AA release but abolished that by phorbol 12-myristate 13-acetate, demonstrating that the Et-1 response was PKC independent. Raised levels of extracellular KCI inhibited both AA release and the increase in [Ca²⁺]_i triggered by Et-1, whereas valinomycin, which causes K⁺ efflux, not only caused a rapid rise in [Ca²⁺]_i but also caused AA mobilisation. The results therefore suggest that Et-1 activation of PLA₂ in this cell type requires calcium influx dependent on K⁺ efflux.     

Inhibition of iloprost of the contractile effect of noradrenaline in mesenteric artery rings: evidence for a possible calcium-dependent mechanism.

Iloprost caused a concentration-dependent decrease in the response to noradrenaline in the rabbit isolated endothelium denuded rings from superior mesenteric artery but not thoracic aorta. Similar inhibition was obtained by verapamil using identical concentrations. In Ca(2+)-free EGTA containing medium noradrenaline both at lower and higher concentrations elicited a reduced contractile response and further addition of Ca2+ (2.5 mM) to the medium produced a second contraction in both mesenteric artery and aortic rings which was significantly and equally inhibited by iloprost and verapamil using identical concentrations in mesenteric artery but not in aortic rings. Prior addition of iloprost to the medium did not protect the inhibitory effect of phenoxybenzamine against noradrenaline-induced contraction. These results were taken as an evidence for the possible Ca2+ entry reducing effect of iloprost in mesenteric artery but not thoracic aorta. These results were also taken as an indirect evidence supporting the hypothesis that increased synthesis of prostacyclin by noradrenaline in the vascular wall may inhibit the contractile effect of the agonist by a (-) feedback mechanism mediated by Ca2+ entry into the vascular smooth muscle.     

Dexmedetomidine suppresses serum syndecan-1 elevation and improves survival in a rat hemorrhagic shock model

Hemorrhagic shock causes vascular endothelial glycocalyx (EGCX) damage and systemic inflammation. Dexmedetomidine (DEX) has anti-inflammatory and EGCX-protective effects, but its effect on hemorrhagic shock has not been investigated. Therefore, we investigated whether DEX reduces inflammation and protects EGCX during hemorrhagic shock. Anesthetized Sprague-Dawley rats were randomly assigned to five groups (n=7 per group): no shock (SHAM), hemorrhagic shock (HS), hemorrhagic shock with DEX (HS+DEX), hemorrhagic shock with DEX and the α7 nicotinic type acetylcholine receptor antagonist methyllycaconitine citrate (HS+DEX/MLA), and hemorrhagic shock with MLA (HS+MLA). HS was induced by shedding blood to a mean blood pressure of 25–30 mmHg, which was maintained for 30 min, after which rats were resuscitated with Ringer’s lactate solution at three times the bleeding volume. The survival rate was assessed up to 3 h after the start of fluid resuscitation. Serum tumor necrosis factor-alpha (TNF-α) and syndecan-1 concentrations, and wet-to-dry ratio of the heart were measured 90 min after the start of fluid resuscitation. The survival rate after 3 h was significantly higher in the HS+DEX group than in the HS group. Serum TNF-α and syndecan-1 concentrations, and the wet-to-dry ratio of heart were elevated by HS, but significantly decreased by DEX. These effects were antagonized by MLA. DEX suppressed the inflammatory response and serum syndecan-1 elevation, and prolonged survival in rats with HS.     

不同组织细胞线粒体数量及功能的休克敏感性研究

摘要 目的：探究不同组织细胞线粒体数量及功能的休克敏感性差异。方法：在整体和细胞水平模拟失血性休克和脓毒性休克模型,通过mtDNA检测、线粒体形态分析和线粒体ROS检测观察休克不同时相点肠组织（肠上皮细胞）、血管组织（血管平滑肌细胞）和心肌组织（心肌细胞）中线粒体数量和功能的变化。结果：对于失血性休克（缺氧）刺激,肠组织线粒体数量的休克敏感性明显强于血管和心肌组织（P<0.05）。肠、血管、心肌组织中线粒体数量明显增多分别开始于失血性休克后0.5小时、1小时和2小时。对于脓毒性休克（LPS）刺激,肠组织线粒体数量的休克敏感性明显弱于血管和心肌组织（P<0.05）。肠、血管、心肌组织中线粒体数量明显增多分别开始于脓毒性休克后9小时、6小时和3小时。只有高浓度长时间LPS刺激才会引起肠上皮细胞线粒体数量的明显增高。各组织细胞线粒体功能对各型休克刺激的敏感性和反应程度虽然存在差异,但都晚于线粒体数量异常的发生（P<0.05）。结论：各型休克的组织器官敏感性差异可能与不同组织细胞中线粒体的休克敏感性不同有关。线粒体数量异常增加是引起休克后线粒体损伤和细胞功能障碍的始动环节,不同组织细胞线粒体的休克敏感性差异也是影响休克组织器官损伤差异的重要原因之一。     

Regulation of pulmonary venous tone in response to muscarinic receptor activation

We investigated cellular mechanisms that mediate or modulate the vascular response to muscarinic receptor activation (ACh) in pulmonary veins (PV). Isometric tension was measured in isolated canine PV rings with endothelium (E+) and without endothelium (E-). Tension and intracellular Ca(2+) concentration ([Ca(2+)](i)) were measured simultaneously in fura-2-loaded E- PV strips. In the absence of preconstriction, ACh (0.01-10 microM) caused dose-dependent contraction in E+ and E- rings. ACh contraction was potentiated by removing the endothelium or by nitric oxide (NO) synthase inhibition (N-nitro-L-arginine methyl ester, P = 0.001). Cyclooxygenase inhibition (indomethacin) reduced ACh contraction in both E+ and E- PV rings (P = 0.013 and P = 0.037, respectively). ACh contraction was attenuated by inhibitors of voltage-operated Ca(2+) channels (nifedipine, P < 0.001), inositol-1,4,5-trisphosphate (IP(3))-mediated Ca(2+) release (2-aminoethoxydiphenyl borate, P = 0.001), PKC (bisindolylmaleimide I, P = 0.001), Rho-kinase (Y-27632, P = 0.002), and tyrosine kinase (TK; tyrphostin 47, P = 0.015) in E- PV rings. ACh (1 microM) caused a leftward shift in the [Ca(2+)](i)-tension relationship (P = 0.015), i.e., ACh increased myofilament Ca(2+) sensitivity. Inhibition of PKC, Rho-kinase, and TK attenuated the ACh-induced increase in myofilament Ca(2+) sensitivity (P < 0.001, P < 0.001, and P = 0.024, respectively). These findings indicate that in canine PV, ACh contraction is modulated by NO and partially mediated by metabolites of the cyclooxygenase pathway and involves Ca(2+) influx through voltage-operated Ca(2+) channels and IP(3)-mediated Ca(2+) release. In addition, ACh induces increased myofilament Ca(2+) sensitivity, which requires the PKC, Rho-kinase, and TK pathways.     

肠淋巴再灌注加重肠系膜上动脉闭塞性休克大鼠肺部炎症反应

目的:研究肠系膜淋巴再灌注对肠系膜上动脉闭塞性(SMAO)休克大鼠肺部炎症反应的影响。方法:24只Wistar雄性大鼠均分为4组:SMAO组,MLR组,SMAO+MLR组,SHAM组。再灌注2h后,迅速留取肺组织,一部分制备组织匀浆,检测细胞间粘附分子(ICAM-1)和晚期糖基化产物受体(RAGE)。再另外选取固定位置肺部组织放入中性甲醛中固定,用于测定肺内HMGB1、RAGE的表达。结果:SMAO与SMAO+MLR组肺部组织匀浆ICAM-1、RAGE含量显著高于MLR与SHAM组,且SMAO+MLR组肺组织匀浆的ICAM-1、RAGE含量高于SMAO组。肺部组织内HMGB1和RAGE在MLR组与SHAM组基本不表达,或少量表达,MLR加重了SMAO休克模型中HMGB1和RAGE的表达。结论:MLR加重SMAO休克大鼠肺部炎症反应,进一步证实肠淋巴途径在SMAO休克发病学中具有重要作用,同时证实HMGB1及RAGE在SMAO休克大鼠的炎症失常反应中起重要作用。     

Pregnancy reduces RhoA/Rho kinase and protein kinase C signaling pathways downstream of thromboxane receptor activation in the rat uterine artery

During pregnancy, reduced vascular responses to constrictors contribute to decreased uterine and total vascular resistance. Thromboxane A(2) (TxA(2)) is a potent vasoconstrictor that exerts its actions via diverse signaling pathways, and its biosynthesis increases in preeclampsia. In this study, we hypothesized that maternal vascular responses to TxA(2) will be attenuated via Rho kinase, PKC, p38 MAPK, and ERK1/2 signaling pathways. Isolated ring segments of uterine and small mesenteric arteries from late pregnant (19-21 days) and virgin rats were suspended in a myograph, and isometric force was measured. Pregnancy did not affect uterine and mesenteric artery responses to the TxA(2) analog U-46619 (10(-9)-10(-5) M), but transduction signals associated with these contractions were different between pregnant and nonpregnant rats. Inhibition of Rho kinase (10(-6) M Y-27632) reduced sensitivity to U-46619 in virgin uterine vessels but did not inhibit these contractions in pregnant uterine arteries and had no effect on mesenteric vessels. Treatment of arterial segments with a PKC inhibitor (10(-6) M bisindolylmaleimide I) reduced U-46619-induced contractions in virgin uterine and mesenteric arteries and in pregnant mesenteric arteries. Pregnant uterine arteries, however, were unresponsive to PKC inhibition. Inhibition of ERK1/2 (10(-5) M PD-98059) and p38 MAPK (10(-5) M SB-203580) reduced U46619-induced contractions in nonpregnant vessels and in pregnant uterine and mesenteric vessels. These data suggest that normal pregnancy does not affect uterine and mesenteric contractile responses to TxA(2) but reduces the contribution of Rho kinase and PKC signaling pathways to these contractions in the uterine vasculature. In contrast, the role of ERK1/2 and p38 MAPK in U-46619-induced uterine contractions remains unchanged with pregnancy. TxA(2)-associated transduction signals and its regulators might present potential targets for the development of new treatments for preeclampsia and other pregnancy-associated vascular diseases.     

载脂蛋白E对低氧诱导小鼠肺动脉平滑肌细胞增殖的影响及其机制*

目的:探讨外源性载脂蛋白E(apoE)对低氧诱导小鼠肺动脉平滑肌细胞(PASMCs)增殖的影响及其机制。方法:采用组织块贴壁法原代培养小鼠PASMCs,取对数生长期PASMCs,分常氧组、常氧+apoE组、低氧组和低氧+apoE组,常氧组培养条件为:21% O₂、5% CO₂,低氧组培养条件为:1% O₂、5% CO₂,外源性加apoE使终浓度为10 μg/ml,培养时间为48 h,重复三次。EdU掺入法检测细胞增殖情况,Western blot法检测apoE、增殖细胞核抗原(PCNA)、蛋白激酶C(PKC)和磷酸化蛋白激酶C(p-PKC)蛋白的表达。结果:与常氧组比较,低氧组PASMCs增殖率提高64.7%,PCNA蛋白和p-PKC蛋白表达分别上调69.0%和120.0%,而apoE蛋白表达下调51.0%(P均＜0.05);与低氧组比较,低氧+apoE组PASMCs增殖率降低19.6%,PCNA蛋白和p-PKC蛋白表达分别下调19.8%和103.2%(P均＜0.05);各组间PKC蛋白表达无显著性差异,常氧组p-PKC蛋白表达与常氧+apoE组的相比也无显著性差异(P均＞0.05)。结论:apoE能抑制低氧诱导小鼠PASMCs增殖,其机制可能与阻碍PKC途径有关。     

刺激腓深神经对低血压或休克狗心血管活动的影响

实验在麻醉狗中进行。静脉内匀速注射硝普钠时,平均动脉压和左心室收缩压明显降低,左心室dp/dt_(max)、-dp/dt_(max)和心力环面积均明显减小。此时电刺激一侧腓深神经可使动脉血压和左心室收缩压明显升高,dp/dt_(max)和心力环面积也显著增加。停止刺激后,动脉血压和左心室收缩压逐渐回向刺激前的水平。停止注射硝普钠5～15分钟后,上述各项观察指标基本恢复到注药前的水平。在用大肠杆菌内毒素造成休克的狗中,电刺激一侧腓深神经,也能使平均动脉压和左心室收缩压升高,同时dp/dt_(max)、-dp/dt_(max)和肠系膜血管阻力明显增高,但肾血管阻力增加不明显。本实验结果与以往的实验资料一起表明,在用扩血管药造成低血压时,躯体神经刺激引起的升压效应似乎以心肌收缩力增加为主;而在内毒素休克时,躯体神经刺激可通过改善心肌收缩功能和增加内脏血管阻力而引起升压作用。