Relaxant effect of amiloride on canine tracheal smooth muscle

Amiloride, a K+-sparing diuretic, relaxed canine tracheal smooth muscle strips contracted isometrically with high potassium (KCl), carbachol, serotonin and histamine. This indicated that relaxation was not linked to an interaction with an agonist specific receptor. Amiloride-induced relaxation was also not mediated through the production of relaxant prostaglandins, or by the endogenous release of catecholamines. During potassium contractions, amiloride addition produced a slow monophasic, dose-dependent relaxation (IC50 = 12.3 microM). In carbachol contracted strips, 1 and 10 microM amiloride induced a slow monophasic relaxation. With 35 to 250 microM, an initial rapid phase (IC50 = 75.5 microM) was superimposed onto this slow phase (IC50 = 23.5 microM), producing a biphasic relaxation. The rates of relaxation decreased with increased external [Na+] regardless of stimulus, suggesting possible competitive inhibition of a sodium-dependent process. Exposure caused a rapid decline in tension followed by a recovery phase. Tension maintenance during potassium contraction decreased transiently upon the addition of acid to a much lesser extent. Amiloride (100 microM) depressed tension recovery after acid exposure in both cases. Based on the known actions of this drug, inhibition of the Na+-H+ antiporter appears to be consistent with these data. This suggests amiloride may well belong to a new class of smooth muscle relaxants.     

Relaxant effect of magnesium and zinc on histamine-induced bronchoconstriction in dogs

OBJECTIVE: Magnesium sulfate (MgSO4) has been reported to produce bronchodilation in asthmatic patients. In vitro studies have suggested that divalent cations inhibit L-type voltage-sensitive calcium ion (Ca2+) channels in cardiac and smooth muscles. In this study, we evaluated the in vitro and in vivo effects of magnesium ion (Mg2+) and zinc ion (Zn2+) on the airway contracted by histamine. SETTING: A university research laboratory. SUBJECTS: IN VITRO: Tracheal smooth muscle from guinea pigs. IN VIVO: Mongrel dogs. MEASUREMENTS AND MAIN RESULTS: IN VITRO STUDY: The tension of isolated guinea pig tracheal strips was measured isometrically with a force displacement transducer. The specimen was contracted with histamine (10 microM). Then, MgSO4 (n = 6), zinc sulfate (ZnSO4, n = 6), or sodium sulfate (Na2SO4, n = 6) was cumulatively added to the organ bath. IN VIVO STUDY: The bronchial cross-sectional area of mongrel dogs was measured by a direct visualization method demonstrated previously. The dogs were randomly assigned to three groups: group Mg (n = 7), group Zn (n = 7), and group Na (n = 7). Bronchoconstriction was elicited with histamine (10 microg/kg plus 500 microg/kg/hr iv). Thirty minutes after the start of histamine infusion, 0 (saline), 1, 10, and 100 micromol/kg ZnSO4 or 1, 10, 100, and 1000 micromol/kg MgSO4 or Na2SO4 were administered intravenously in group Zn, Mg, or Na, respectively. The bronchial cross-sectional area was assessed before (basal) and 30 mins after the start of histamine infusion and 5 mins after each dose of ZnSO4, MgSO4, or Na2SO4. Arterial blood was also obtained to measure plasma levels of epinephrine and norepinephrine by gas chromatography-mass spectrometry. All data are expressed as mean +/- SEM. The doses of the divalent cations that reversed histamine-induced contraction by 50% were calculated by GraphPad Prism. MgSO4 and ZnSO4 (9.38+/-0.28 and 1.84+/-0.30 mM, respectively) relaxed histamine-contracted tracheal strip in a concentration-dependent manner, whereas Na2SO4 did not. Similarly, the in vivo study showed that MgSO4 and ZnSO4 dose-dependently reversed histamine-induced bronchoconstriction (potency, ZnSO4 > MgSO4), whereas Na2SO4 did not. In groups Mg and Zn, the plasma catecholamine levels also dose-dependently increased except when 1000 micromol/kg MgSO4 was administered. CONCLUSION: Because the divalent cations tested produced a spasmolytic effect on the contracted airway, infusion of divalent cations might be effective against asthmatic attack. However, high concentrations of these cations produce significant toxicity, so dosage will be an important concern in development of these agents.     

血管内皮细胞生长因子在兔骨髓基质干细胞内的表达及影响

目的:构建血管内皮细胞生长因子pcDNA3/hVEGF165真核表达载体,并用脂质体法转染骨髓基质干细胞(mesenchymalstemcells,MSCs),观察血管内皮细胞生长因子(vascularendothelialgrowthfactor,VEGF)转染后对骨髓MSCs的生长、转化的影响。方法:采用贴壁法分离骨髓MSCs,脂质体法转染。100g/L胎牛血清DMEM培养MSCs,计数法绘制生长曲线,特殊染色观察MSCs的转化,免疫组织化学法观察转染后VEGF的表达。结果:转染了pcDNA3/hVEGF165的骨髓MSCs胞浆内出现VEGF阳性颗粒,而转染了pcDNA3组及未转染组中未出现阳性颗粒,生长曲线在3组中无明显差别。特殊染色出现的时间亦无明显差别。而且,注射有转染了pcDNA3/hVEGF165的MSCs的大白兔局部皮下血管数量增加,其他两组未发现。结论:本实验成功构建了pcDNA3/hVEGF165真核表达载体并能够在MSCs细胞内表达VEGF,其表达产物具有血管内皮增殖刺激活性。     

动态增强MRI定量监测血管阻断剂治疗兔VX2种植性肝癌的效果

目的 评价采用动态增强MRI(DCE-MRI)定量监测血管阻断剂治疗兔VX2种植性肝癌的效果。方法 成功建立28只兔VX2种植性肝癌模型,以数字法随机等分为2组,分别给予血管阻断剂M410(治疗组)和生理盐水(对照组)。给药前(基线时间点baseline)、给药后4 h、1天、4天、7天、14天分别行MR平扫及DCE-MRI,并于每个时间点取肿瘤组织行病理检查(HE及CD34免疫组化染色),观察两组肿瘤体积、对比剂容积转移常量(K^trans)、各时间点肿瘤K^trans变化率(ΔK^trans)及病理结果的变化。结果 治疗组肿瘤较对照组生长缓慢,给药后第4天、7天、14天,两组肿瘤体积差异有统计学意义(P<0.05)。治疗组K^trans值于给药4 h后降低,至4天达最低,随后逐渐恢复,于14天时接近处理前水平。给药后4 h、1天、4天治疗组的K^trans值较对照组明显降低(P<0.05),余各时间点K^trans值两组差异均无统计学意义(P>0.05)。两组各时间点ΔK^trans%变化趋势与K^trans值变化趋势相同。DCE-MRI血管功能参数值改变与肿瘤组织HE及CD 34染色结果相符。结论 DCE-MRI可动态定量评价血管阻断剂治疗兔VX2种植性肝癌后肿瘤组织的变化,是肿瘤血管靶向治疗后监测和评价疗效的理想的影像学手段。     

吡格列酮对兔动脉粥样硬化模型血管壁炎症因子的影响

目的:探讨吡格列酮时血管壁炎症因子的影响.方法:55只新西兰兔随机分成5组:A组,正常对照:B组,正常+低剂量吡格列酮(PIO);C组,病理对照;D组,病理+低剂量PIO;E组,病理+高剂量PIO.实验前后抽血测C反应蛋白(CRP),采用免疫组化检测动脉粥样硬化(AS)病变中巨噬细胞浸润程度.结果:PIO可降低AS兔CRP(P＜0.05),抑制巨噬细胞在斑块内浸润(P＜0.05),高剂量较低剂量作用更明显(P＜0.05).结论:PIO具有抑制粥样硬化血管壁炎症的作用.     

Relaxant effects of beta-carbolines on rat aortic rings.

The effects of two beta-carbolines, methyl 6,7-dimethoxy-4-ethyl-beta- carboline-3-carboxylate (DMCM) and ethyl beta-carboline-3-carboxylate (beta CCE) were assayed on rat aortic rings precontracted with different agonists. The beta-carbolines tested induced a concentration-dependent (2-200 microM) relaxation of aortic rings precontracted with 30 mM KCl. This relaxation was not modified by the removal of the rat aortic endothelium. Contractions elicited by the activation of either voltage-gated calcium channels (0.05 microM BAY K 8644) or receptor-operated calcium channels (0.1 microM norepinephrine), as well as contractions produced by the entry of calcium as a lipid-soluble complex (10 microM A23187), were also reduced by DMCM and by beta CCE. In addition, whereas DMCM did not modify calmodulin activity, both beta-carbolines inhibited in a concentration-dependent manner (0.6-200 microM) the rat aortic cyclic nucleotide phosphodiesterase activity. Moreover, DMCM as well as beta CCE potentiated the relaxation of K(+)-contracted aortic rings induced by the stimulation of either adenylyl cyclase with forskolin (0.1-1 microM) or guanylyl cyclase with sodium nitroprusside (0.1-100 nM). The intracellular rat aortic levels of cyclic AMP measured in the presence of 0.1 microM forskolin were increased by 100% in the presence of DMCM. On the other hand, 6 microM DMCM potentiated the relaxation induced by nifedipine in K(+)-contracted aortic rings, whereas the K+ channel blocker 10 mM tetraethylammonium did not modify the relaxation elicited by DMCM in the norepinephrine-contracted preparation.(ABSTRACT TRUNCATED AT 250 WORDS)     

兔血管内皮细胞和诱导成骨细胞在可注射纳米材料上的共培养

目的：将可注射纳米骨材料与共培养的兔肾血管内皮细胞和兔骨髓间充质干细胞诱导的成骨细胞复合,并构建可注射细胞型纳米组织工程骨,观察它们体外培养的相容性. 方法：实验于2003-09/2004-11在苏州大学附属儿童医院完成.①实验材料：取16周龄雄性新西兰大耳白兔,体质量1.5 kg左右.②实验方法：麻醉后抽取兔骨髓,用淋巴细胞分离液分离出其中的间充质干细胞,在含体积分数为0.15牛血清的RPMI1640液中培养.骨髓间充质干细胞在条件培养基中,7 d后可见细胞变为多边形,碱性磷酸酶和Ⅰ型胶原染色阳性,形成钙结节,表现成骨细胞分化特点.采用三步梯度筛网法,获得肾血管球,5 g/L胶原酶Ⅳ37℃消化15～20 min,离心沉淀获取血管内皮细胞,在含体积分数为0.15小牛血清的M199中培养.③实验评估：免疫组织化学法进行第Ⅷ因子相关抗原鉴定,透射电镜观察细胞浆Weibel-Palade小体,间接免疫荧光法检测CD31、CD34及CD44的表达.将共培养的兔肾血管内皮细胞、成骨细胞与可注射纳米骨材料体外复合培养,进行形态学观察和功能测定. 结果：①在一定培养条件下成功诱导兔骨髓间充质干细胞向成骨细胞分化.②培养的血管内皮细胞免疫组织化学法检测第Ⅷ因子相关抗原阳性,透射电镜观察到细胞浆中的Weibel-Palade小体,间接免疫荧光法检测CD31、CD34表达阳性,CD44阴性.③共培养的兔肾血管内皮细胞、成骨细胞在可注射纳米骨材料上生长、增殖良好,细胞活性和碱性磷酸酶活性未受到影响. 结论：可注射纳米骨材料具有良好的细胞相容性,可作为骨组织工程理想的可注射载体材料.     

Variation in contractile response characteristics of rabbit aorta strips with surface of drug entry.

Contractile responses of rabbit aorta strips to norepinephrine in the presence of cocaine, histamine and serotonin entering through the intima have been compared with those when these drugs enter via the adventitia. The responses to entry through the inner compared with the outer surface occur after a shorter latency, rise at a greater initial velocity and reach a high steady state. Differences persist after removal of the tunica adventitia. Responses of strips to intimal entry appear identical to those of the intact strip. These results suggest an asymmetry of vascular smooth muscle cell characteristics across the thickness of the tunica media of the rabbit thoracic aorta.     

Regional vascular responses to asphyxia in the rabbit

Organ blood flow was measured in eight spontaneously breathing male New Zealand white rabbits exposed to a 50 min period of asphyxia. The results were compared with eight control animals. Cardiac output and arterial pressure did not change. There was increased flow to the heart, brain and diaphragm. Flow to the kidneys and adipose tissue was reduced. Flow to the gastro-intestinal tract, liver, skeletal muscle and carcass was unchanged. Prolonged moderate asphyxia produces preferential blood supply to vital organs and maintains flow to the skeletal musculature and the gastro-intestinal tract; their blood supply is diverted mainly from the kidneys. These changes are similar to those seen in haemorrhagic and endotoxic shock in the rabbit.     

延胡索对未孕大鼠离体子宫平滑肌运动的抑制作用

目的:观察延胡索乙素对未孕大鼠离体子宫平滑肌条运动的抑制作用。方法:实验于2003-11/2004-03在兰州大学医学院生理学教研室进行。①成年未孕Wistar大鼠90只,于实验前72h皮下注射乙烯雌酚0.5mg/kg,造成人工动情期以提高子宫对药物的敏感性。②猛击大鼠头部致昏,取卵巢及子宫分叉处之间的中段子宫,制成8mm×2mm的肌条,将肌条安置在恒温平滑肌肌槽中,每个肌槽中分别盛有5mL37℃Krebs液。③肌条在1g的前负荷下温育,每20min更换一次5mL新鲜的Krebs液(37℃),待肌条的自发活动平稳后加入不同剂量的延胡索乙素(2×10-5,2×10-4,4×10-4,8×10-4,1.6×10-3kg/L),观察延胡索乙素对大鼠离体子宫平滑肌条收缩活动的影响。④分别加入不同的受体拮抗剂5min后(2×10-6mol/L酚妥拉明,2×10-7mol/L异搏定,2×10-5mol/吲哚美辛和2×10-6mol/L苯海拉明),再加入8×10-4延胡索乙素,观察使用拮抗剂后延胡索乙素对大鼠离体子宫平滑肌条作用的影响。⑤计算给药前5min和给药后5min子宫平滑肌条的收缩波的频率、平均振幅和收缩波间隔平均持续时间。结果:①不同浓度的延胡索乙素均能抑制子宫平滑肌收缩运动,可使子宫平滑肌收缩波的频率减慢,在延胡索乙素浓度8×10-4kg/L,1.6×10-3kg/L时为其抑制作用差异具有显著性(P<0.01);延胡索乙素各浓度虽可以降低子宫平滑肌收缩波的振幅但差异无显著性(P>0.05);而当延胡索乙素浓度为4×10-4,8×10-4,1.6×10-3kg/L时,可显著延长收缩波的间歇时间(P<0.01)。②在加入H1受体阻断剂苯海拉明后延胡索乙素使子宫平滑肌的收缩频率降低(P<0.05),收缩波间隔的持续时间延长(P<0.05),而收缩振幅增高(P<0.05);在加入α受体阻断剂酚妥拉明后,延胡索乙素抑制子宫平滑肌的作用与单独使用延胡索乙素组相比差异无显著性(P>0.05);在加入吲哚美辛抑制前列腺素合成酶合成和释放后,延胡索乙素抑制子宫平滑肌的作用与延胡索乙素组相比仍然可以使收缩波的频率降低(P<0.05),振幅减小(P<0.05),收缩波间隔持续时间延长(P<0.05)。加入L型Ca2 通道阻断剂异搏定后延胡索乙素对未孕大鼠离体子宫平滑肌的运动有抑制作用,收缩间隔时间延长(P<0.05),但振幅不变(P<0.05)。结论:延胡索乙素抑制大鼠子宫平滑肌收缩运动的部分作用可能与L型电压依从性Ca2 通道使平滑肌细胞内Ca2 浓度降低有关,也可能与前列腺素的合成与释放有关。     

七叶皂苷钠静脉输液速度对兔耳缘静脉血管影响的实验研究

[目的]了解七叶皂苷钠输液速度与静脉炎发生的关系,为临床护士科学合理调整七叶皂苷钠输液速度提供理论支持和理论依据.[方法]将日本大耳白兔随机分为4组,分别为A组、B组、C组和空白对照组.A组输液速度为30 gtt/min,B组输液速度为50gtt/min,C组输液速度为80 gtt/min.每组6只,双耳同时输液,每组标本12个.将4 mg七叶皂苷钠溶于10 mL0.9％氯化钠注射液中,给药容量10 mL,给药1次,给药12 h后从肉眼观察和病理组织变化两方面对兔耳缘输液静脉血管进行评价.[结果]A组、B组、C组均发生静脉炎,A组静脉炎发生率较其他组高;A组、C组静脉血管周围组织水肿程度较B组高.[结论]输液速度对静脉炎的发生有一定影响,减慢输液速度并不能降低七叶皂苷钠对静脉血管的损害,适当加快输液速度可以降低七叶皂苷钠致静脉炎的发生率.