化学药物对家兔离体小肠平滑肌电生理特性的影响

观察各种化学药物对家兔离体小肠各段平滑肌的作用,采用常规离体灌流的十二指肠、空肠及回肠平滑肌标本作舒缩运动实验,记录用药前后各段小肠平滑肌的收缩活动特征及变化规律.结果显示：不同浓度的乙酰胆碱和磷酸组织胺能增强小肠各段平滑肌的收缩频率与幅度,其幅值变化与用药前有显著性差异（P＜0.01） ,并呈剂量依赖性;而不同浓度的肾上腺素和阿托品则抑制小肠各段平滑肌（P＜0.01） .不同肠段对各种化学药物的作用存在着差异,一般十二指肠作用最强,空肠次之,回肠最差.     

番木瓜叶提取物对兔离体十二指肠收缩运动的影响

为了观察番木瓜叶提取物(Carica papaya leaf extracts,CPL)对于兔离体十二指肠平滑肌收缩的影响,并探讨其作用机制,以生物信号采集系统记录终浓度分别是1.0、1.5、2.0、2.5 g/L的CPL对兔离体十二指肠平滑肌收缩运动的影响;并观察将CPL分别与肠动力激动剂(乙酰胆碱和组胺)和肠动力抑...     

离体子宫平滑肌测定方法的改进

目的:探索离体子宫平滑肌测定方法中,使用增氧泵通气取代混合氧为离体子宫平滑肌供氧的可行性。方法:采用RM-6240BD多道生理信号采集处理系统,观察营养液内通入混合氧、增氧泵通气及无通气对离体子宫平滑肌活动力的影响。结果:与营养液内通入混合氧相比,离体子宫平滑肌的活动力在混合氧组与增氧泵通气组间无统计学差异(P0.05),不通气组的频率和活动力均有统计学差异(P0.05或P0.01)。结论:可以使用增氧泵通气为离体子宫平滑肌供氧,既满足了供氧,同时也可促进营养液流动,使离体子宫与营养液充分接触。     

银杏叶提取物对小鼠离体小肠平滑肌收缩特性的影响

目的观察不同浓度的银杏叶提取物(Extract of Ginkgo biloba, EGb)对小鼠离体小肠平滑肌活动的影响,探讨EGb对小肠平滑肌的作用机制.方法制备离体肠段标本,灌流给药后记录不同浓度EGb作用下小肠收缩变化.结果低浓度和中浓度的EGb对离体小肠平滑肌有兴奋作用,随浓度增加,低浓度EGb的兴奋程度呈降低趋势,中浓度EGb的兴奋程度呈升高趋势;高浓度EGb引发抑制效应,随浓度增加,抑制程度降低.结论不同浓度范围的EGb对离体小肠平滑肌有不同作用,可能通过对平滑肌的直接作用或调节激素释放,影响离子通道等途径发挥作用.     

姜黄素对小鼠离体十二指肠平滑肌舒缩活动的影响

目的:本研究采用小鼠离体十二指肠平滑肌观察姜黄素对胃肠道蠕动的影响,探讨其作用机制。方法:取小鼠离体十二指肠平滑肌条,放入37℃Krebs液浴槽中,通入95%氧气和5%二氧化碳混合气体,分组进行下列实验:对照组和分别加入10-40 M姜黄素组,测量记录十二指肠平滑肌的自主收缩变化;另取一组平滑肌条,分对照组、乙酰胆碱组、乙酰胆碱+姜黄素组、阿托品组、阿托品+姜黄素组,采用张力换能器连接多通道生理信号采集处理系统,测量比较十二指肠平滑肌舒缩的变化。结果:小鼠十二指肠平滑肌加入姜黄素孵育后,其自主收缩幅度有明显下降(P0.01),而且降低的幅度与姜黄素剂量相关;给与乙酰胆碱引起十二指肠收缩后,再加姜黄素孵育,十二指肠平滑肌的收缩幅度明显的下降(P0.01);给予阿托品引起小鼠平滑肌舒张后,再给予姜黄素孵育,平滑肌收缩幅度进一步降低。结论:姜黄素对小鼠离体十二指肠平滑肌具有直接舒张作用。     

磁场处理离体小肠对葡萄糖吸收功能的影响

目的 :观察磁场处理离体小肠对葡萄糖吸收功能的影响。方法 :用经 0 .1T和 0 .2 5T磁场处理小白鼠离体小肠 ,分别测定其对葡萄糖的吸收值。结果 :用 0 .1T和 0 .2 5T磁场处理的小白鼠离体小肠浆膜侧吸收葡萄糖的量与对照组比较 ,0 .1T差异显著 (p <0 .0 5 ) ,0 .2 5T的差异极显著 (p <0 .0 1 )。结论 :用0 .1T和 0 .2 5T磁场处理的小白鼠离体小肠对葡萄糖的吸收均有明显的促进作用。     

三唑酮对离体黄瓜子叶膜系统的影响

研究了三唑酮处理后离体黄瓜子叶衰老过程中活性氧的产生及膜系统有变化。结果表明：20mg/L三唑酮能有效抑制O^-2.、H2O3的累积,减轻质膜相对透性和膜脂过氧化程度及组织自动氧化速率。这表明三唑酮减轻了活性氧在植物体内的累积,可以作为一种活性氧的直接或间接清除剂。     

氢溴酸高乌甲素对小肠平滑肌运动的作用

目的：研究氢溴酸高乌甲素对小肠平滑肌运动的影响并探讨其可能的作用机制。方法：记录氢溴酸高乌甲素对家兔离体小肠平滑肌运动的影响,并测定氢溴酸高乌甲素处理后小鼠小肠推进运动的变化。结果：氢溴酸高乌甲素抑制家兔离体小肠平滑肌收缩的发展张力。纳洛酮对氢溴酸高乌甲素的肠肌抑制作用无明显影响（P〉0.05）。乙酰胆碱（0.1 mg/L）可使家兔小肠舒张末张力明显增加。氢溴酸高乌甲素处理后,乙酰胆碱对肠肌舒张末张力的增加百分比降低（P〈0.05）。氢溴酸高乌甲素对小鼠小肠推进运动有显著抑制作用（P〈0.05）。结论：氢溴酸高乌甲素对小肠平滑肌收缩有抑制作用,并可以部分阻断乙酰胆碱的肠肌收缩作用,阿片受体可能不参与该抑制作用。     

三七总皂苷对家兔离体小肠平滑肌自发收缩活动的影响

目的：观察三七总皂苷对家兔离体小肠平滑肌收缩活动的影响,并探讨其作用机制。方法：取健康家兔,雌雄不拘,将小肠离体后恒温灌流,观察三七总皂苷对家兔小肠自发收缩活动的影响;在灌流液中分别加入BayK8644、左旋硝基精氨酸甲酯（L-NAME）后再加入三七总皂苷,研究其作用机制;在无钙台式液中加入rynodine后再加入三七总皂苷,研究其作用机制。结果：三七总皂苷剂量依赖性的抑制家兔离体小肠平滑肌收缩的幅度。BayK8644和L-NAME均可完全阻断三七总皂苷对家兔小肠平滑肌收缩活动的抑制作用。在无钙台式液中,三七总皂苷显著抑制rynodine引起的细胞内钙收缩活动。结论：三七总皂苷显著抑制家兔小肠平滑肌的收缩活动,其抑制收缩活动机制可能是：增加小肠平滑肌NO浓度,从而抑制细胞外钙内流和内钙释放。     

Differentiation of the zebrafish enteric nervous system and intestinal smooth muscle

Development of the enteric nervous system is critical for normal functioning of the digestive system. In vertebrates, enteric precursors originate from the neural crest and migrate into the digestive system. Enteric neurons enable the digestive system to sense and respond to local conditions without the need for central nervous system input. Here we describe major steps in differentiation of the zebrafish enteric nervous system. During migration and neural differentiation of enteric precursors, we identify regions of the enteric nervous system in different phases of differentiation. Early in migration, a small group of anterior enteric neurons are first to form. This is followed by an anterior to posterior wave of enteric neural differentiation later in the migratory phase. Enteric precursors continue proliferating and differentiating into the third day of embryogenesis. nNOS neurons form early while serotonin neurons form late toward the end of enteric neural differentiation. Numbers of enteric neurons increase gradually except during periods of circular and longitudinal intestinal smooth muscle differentiation.     

大黄素对大鼠离体空肠平滑肌收缩的影响

目的：观察大黄素（emodin）对大鼠离体空肠平滑肌收缩功能的影响,并探讨其作用机制。方法：大鼠离体空肠标本随机分为7组（n=6）：对照组,大黄素剂量组（1,5,10,20μmol／L）,普萘洛尔（PRO）加大黄素组,格列苯脲（GLI）加大黄素组,NG-基-L厂精氨酸甲酯（1．NAME）加大黄素组,无钙K-H液对照组及无钙K-H液大黄素组。采用颈椎离断法处死大鼠并分离其空肠,将肠段标本与张力换能器相连并置于氧饱和的K-H液中。采用BL-420E＋生物信号采集处理系统记录大鼠空肠平滑肌的收缩张力（TE）,幅度（AM）和频率（FR）的影响。结果：①大黄素能使大鼠离体空肠平滑肌的收缩张力和幅度明显下降,且呈剂量依赖性（P〈0．05,P〈0．01）;对频率无明显影响。②普萘洛尔（P〈0．05）、格列苯脲（P〈0．01）可部分阻断大黄素对空肠平滑肌的抑制作用。③L．NAME对大黄素所引起的空肠平滑肌的抑制作用无影响。④氯化钙所引起的空肠平滑肌收缩可被大黄素所抑制（P〈0．01）。结论：大黄素能明显减弱大鼠离体空肠平滑肌的收缩张力和收缩幅度,对收缩频率无影响。这种作用可能是通过兴奋肾上腺素8受体、兴奋ATP敏感钾通道、阻断细胞膜上钙离子通道实现。     

The effect of TGF-beta receptor binding peptides on smooth muscle cells

TGF-beta1 is a potent regulator of vascular smooth muscle cell (VSMC) proliferation, migration, and extracellular matrix (ECM) synthesis. In this study, we selected two peptides, IM-1 and IM-2, that bind to the TGF-beta type II receptor (TGF-beta RII) using phage display. IM-1 and IM-2 bind to the TGF-beta RII, with a K(d) of 1 microM. Like TGF-beta, IM-1 induced VSMC chemotaxis and PAI-1 mRNA expression, as determined using Boyden chambers and real time quantitative PCR. In contrast, IM-2 had no effect on VSMC chemotaxis or PAI-1 induction. Induction of ECM synthesis, involving proteins such as osteopontin and alpha-smooth muscle actin, was determined by ELISA. Osteopontin expression was inhibited by both peptides, but TGF-beta-induced alpha-smooth muscle actin expression could only be inhibited by IM-1. In conclusion, IM-1 activity on VSMC is agonistic with TGF-beta, except for ECM synthesis, whereas the IM-2 peptide is antagonistic for some examined TGF-beta functions.     

The effect of the Fusarium metabolite beauvericin on electromechanical and -physiological properties in isolated smooth and heart muscle preparations of guinea pigs

The electromechanical and -physiological effects of beauvericin were studied in isolated smooth and heart muscle preparations of the guinea pig. Beauvericin concentration-dependently decreased the force of contraction in precontracted (60 mM KCl) terminal ilea with an IC₅₀ of 0.86 M, and in electrically stimulated (1 Hz) papillary muscles with an IC₅₀ of 18 M. This negative inotropic effect in papillary muscles was antagonised in a non-competitive way by increased extracellular calcium concentrations. Spontaneous activity in right atria was affected at concentrations >10 M beauvericin. The negative chronotropic effect was less pronounced than the negative inotropic effect. In action potentials of electrically driven (1 Hz) papillary muscles, 10 M beauvericin significantly decreased membrane resting potential until unexcitability of the preparation occurred. Despite depolarisation of the membrane the maximum rate of rise of the action potential was not changed. The action potential duration was shortened, but the decrease was only significant at times to 20% and 50% repolarisation. These data, derived from the electrophysiological experiments, not only imply an effect on the calcium current as suggested by the effects on contractility, but also an interaction with the sodium inward and potassium outward currents.This revised version was published online in October 2005 with corrections to the Cover Date.     

A paradoxical pro-apoptotic effect of thrombin on smooth muscle cells

Whereas thrombin (below 10 nM) is a potent mitogen, recent studies report that exposure to higher doses of thrombin could lead to apoptosis of neurons and tumor cells. Our results show that prolonged exposure (> or = 24 h) to thrombin (50-100 nM) exerts a pro-apoptotic effect on cultured vascular smooth muscle cells (VSMCs). This phenomenon depends on thrombin serine-protease activity but is independent of PAR-1 and -4 activation and subsequent signaling. The parallel occurrence of cell retraction and cleavage of fibronectin suggests that thrombin-induced apoptosis is consecutive to pericellular proteolysis. These data point to a new potential action of thrombin in the cardiovascular system.     

A two-filament system and interaction of heavy meromyosin (HMM) with thin filaments in smooth muscle

Summary The structure of glycerinated smooth muscle from small intestine of adult rat was investigated by electron microscopy. In the central parts of the tissue blocks a two-filament system was found, consisting of parallel thick and thin filaments with regularly spaced interconnections, closely resembling that of striated muscle. In the peripheral parts of the blocks only thin filaments were found. The thin filaments were identified as actin by the formation of arrowhead complexes after incubation with heavy meromyosin.This work was supported by grants from the Danish State Research Foundation and the Tuborg Foundation to J. Rostgaard.     

The effect of vitamin E on the response of rabbit bladder smooth muscle to hydrogen peroxide

There is increasing evidence that ischemia, reperfusion, and the generation of free radicals are major etiological factors in the progression of bladder dysfunction after partial outlet obstruction. In vitro studies demonstrated that the magnitude of contractile dysfunction following exposure of bladder smooth muscle to hypoxia followed by re-oxygenation was related to the level of lipid peroxidation indicating that membrane lipid peroxidation participated in the contractile failure induced. Recent studies demonstrated that incubation of isolated strips of bladder smooth muscle with hydrogen peroxide (H₂O₂) result in progressive contractile dysfunctions and is associated with progressive increases in MDA (peroxidation product). The current study investigates if feeding rabbits a diet high in vitamin E protects the bladder from the effects of in vitro H₂O₂. Sixty-four male New Zealand White rabbits were separated into two groups: The rabbits in group 1 were fed a normal diet (28 rabbits) whereas the rabbits in group 2 were placed on a diet enriched with -tocopherol (36 rabbits). After 3 weeks on the normal or high E diet, each rabbit was anesthetized and the bladder excised and cut into 6 isolated strips of bladder detrusor. Each strip was mounted in individual 15 ml baths containing oxygenated Tyrode's solution. The contractile responses to field stimulation (FS), carbachol, and KCl were determined. The strips were washed and exposed to one of the following concentrations of hydrogen peroxide (H₂O₂): 0% (control), 0.0625, 0.125, 0.25, 0.5, 1.0 and 3.0% for a period of 1 h. At the end of the hour each strip was washed free of H₂O₂ and a second set of contractile responses were performed and compared to the first set. At the end of the experiment, each strip was frozen and stored at –70°C for analysis of malondialdehyde (MDA) as a measure of peroxidation. In both groups, H₂O₂ produced similar dose dependent decreases in the contractile responses to all forms of stimulation. In the normal-diet group H₂O₂ produced a dose dependent increase in MDA formation, whereas in the high E group there were no increases in MDA at any concentration of H₂O₂. Feeding rabbits a diet high in vitamin E protected the bladder smooth muscle from peroxidation, but had no significant effect on the contractile dysfunctions mediated by direct incubation with H₂O₂.