马来酸曲美布汀对束缚应激大鼠离体结肠平滑肌张力的调节作用机制

目的 研究曲美布汀对离体结肠平滑肌收缩及舒张运动的作用机制。方法 建立束缚应激诱发排便异常大鼠动物模型，制备离体结肠平滑肌环行肌及纵行肌肌条，应用张力换能器测定其肌张力。结果 束缚应激大鼠平滑肌肌条在基础状态时，曲美布汀可增加环行肌肌条张力，且随着浓度的递增平滑肌肌条张力有增加倾向。低于10^-7g／ml曲美布汀可增加纵行肌肌条张力，但高于10^-6g／ml时则降低肌条张力。曲美布汀可降低K^ 及乙酰胆碱作用下的束缚应激大鼠环行肌及纵行肌肌条张力，随着浓度的递增曲美布汀舒张平滑肌的作用有增加倾向。在Ca^2 作用下，10^-8g／ml曲美布汀增加束缚应激大鼠纵行肌及环行肌肌条张力，但高于10^-7g／ml时降低肌条的张力。结论 曲美布汀具有抑制和兴奋平滑肌双重作用，作用特点是调节平滑肌收缩与舒张运动，纠正肠管平滑肌运动异常。     

曲美布汀对肠易激综合征治疗机制的研究

目的:通过制备模拟人肠易激综合征(IBS)的束缚应激(wrap restraint stress,WRS)诱发大鼠排便异常变化的实验动物模型,研究曲美布汀对离体结肠平滑肌的异常收缩的调节机制。方法:建立束缚应激大鼠动物模型,制备离体结肠平滑     

钙稳态失衡在致结肠平滑肌收缩性改变中的作用

目的　探讨应激大鼠结肠平滑肌收缩时细胞内外钙离子 (Ca2 +)利用异常、细胞内钙稳态失衡在导致其收缩性改变中的作用。方法　建立寒冷 束缚应激大鼠排便异常的动物模型 ;测定离体结肠环形平滑肌收缩张力 ;差速离心制备结肠平滑肌肌浆网 ,测定肌浆网Ca2 + ATP酶活性。结果　应激大鼠结肠平滑肌收缩活性明显增强 ,并受Ca2 +通道阻滞剂显著抑制。应激大鼠结肠平滑肌肌浆网Ca2 + ATP酶活性降低 5 6 % (P <0 .0 5 )。结论　应激大鼠结肠环形平滑肌收缩活性显著增强 ,可能和肌细胞收缩时细胞外Ca2 +内流增加 ,肌浆网贮存Ca2 +释放减少、Ca2 + ATP酶活性降低等因素导致细胞内钙稳态失衡有关     

羟基红花黄色素A对大鼠避水应激所致结肠高动力的抑制作用及其机制

目的通过体内和体外研究探讨羟基红花黄色素(hydroxy safflower yellow A,HSYA)在大鼠应激性结肠高动力中的作用及其可能的作用机制。方法将15只雄性Wistar大鼠分为3组,分别为:SWAS(假性避水应激)组、WAS(避水应激)组、WAS+HSYA组,每组5只。WAS组和SWAS组大鼠连续10 d每天分别暴露于避水应激和假性避水应激中1 h,建立大鼠模型;WAS+HSYA组大鼠于每天进行避水应激前半小时,以60 mg/kg的HSYA灌胃,而WAS组以相同的生理盐水灌胃,SWAS组则不做处理。整个实验期间,分别记录各组大鼠的每天粪球排出量。于实验第11天,大鼠处死后取近端结肠制备肌条,以张力换能器测定结肠平滑肌肌张力变化。另取正常大鼠离体近端结肠制备肌条,以张力换能器测定结肠平滑肌肌张力变化,当出现一段规律收缩信号后,分别进行其他的相关处理:(1)加入浓度梯度的HSYA溶液(终浓度分别为0.6、1.2、1.8 mol/L),观察并记录其自发性收缩活性变化;(2)用1μmol/L TTX孵育肌条10 min,再以浓度梯度的HSYA溶液处理肌条,观察并记录其自发性收缩活性变化;(3)用30μmol/L Tak-242孵育肌条15 min,再以浓度梯度的HSYA溶液处理肌条,观察并记录其自发性收缩活性的变化。采用SPSS 26.0统计软件、Graphpad 8.0软件对实验所得数据进行分析。结果避水应激诱发大鼠结肠动力亢进。HSYA明显抑制结肠肌条收缩活性,这种作用未被TTX阻断,而TLR4受体拮抗剂Tak-242能显著阻断HSYA对结肠肌条收缩活性的抑制作用。结论 HSYA能逆转应激性结肠动力亢进,这种效应可能与TLR4受体通路有关。     

白细胞介素-6介导抑郁模型大鼠结肠变化的机制研究

目的 研究慢性应激抑郁模型大鼠结肠动力变化、血清白细胞介素(IL)-6与抑郁的关系及对离体结肠肌条收缩的影响.方法 健康成年Wistar大鼠30只,其中15只建立慢性应激抑郁模型,其余15只为对照组.以糖水偏爱实验检测两组大鼠的糖水消耗与体质量比、糖水偏爱百分比.以旷场实验检测两组大鼠的行为学变化.以模拟粪便排出实验评价结肠动力.以酶联免疫吸附测定(ELISA)检测血清IL-6水平.逆转录(RT)-PCR检测结肠组织中IL-6 mRNA水平.检测大鼠离体结肠肌条的收缩功能.用不同浓度的IL-6处理对照组结肠肌条,检测IL-6对正常结肠肌条的影响及其对乙酰胆碱(Ach)的反应.结果 模型组大鼠糖水消耗与体质量比为0.12±0.03、糖水偏爱百分比为(16.17±2.61)％、总行程为(741.54±341.10)cm、直立次数为(15.69±8.00)次,均显著低于对照组[0.18±0.02、(25.54±2.32)％、(1336.20±698.80)cm、(24.87±7.90)次,P值分别=0.041、0.044、0.002、0.001].模型组大鼠粪便排出时间为(109.78±48.00)min,较对照组明显延长[(28.00±11.10) min,P=0.002].模型组大鼠血清和结肠组织IL-6水平均较高.模型组离体结肠肌条对Ach反应弱于对照组(P=0.035).对照组离体结肠肌条对200、500、1000 pg/mlIL-6的反应差异均无统计学意义(P值分别=0.935、0.825和0.766),再加入Ach后,500和1000pg/ml IL-6组对Ach的反应(R值分别为1.15±0.10和1.14±0.15)与对照组单加Ach时的R值(1.61±0.45)比较,差异均有统计学意义(P值分别=0.000、0.004).结论 慢性应激抑郁模型大鼠血清及结肠组织IL-6水平上升,并通过降低肠道对Ach的敏感性而导致平滑肌收缩障碍.     

多潘立酮在增强结肠运动中的作用

目的 观察多潘立酮对结肠的促动力作用,并与莫沙必利及西沙必利比较.方法 ①在体实验:将40只大鼠分为对照组、多潘立酮组、莫沙必利组和西沙必利组,每组10只.在各组大鼠近端结肠和远端结肠埋植应力传感器,记录清醒大鼠结肠运动.②离体实验:在恒温灌流肌槽中,采用张力传感器测定多巴胺和多巴胺+多潘立酮对大鼠离体结肠肌条的收缩活动.结果 在体实验:①清醒大鼠在消化间期的静息状态下,结肠呈现节律性相位收缩活动.②多潘立酮可明显增加结肠的收缩活动,使近端结肠和远端结肠平均振幅分别比对照组增加84.61%±7.26%和76.37%±8.47%,呈剂量-效应关系.同等剂量的莫沙必利对近端结肠和远端结肠平均振幅分别比对照组增加50.32%±8.16%和45.13%±7.16%.莫沙必利对结肠的促动力作用明显低于多潘立酮.而同等剂量的西沙必利对近端结肠和远端结肠平均振幅分别比对照组增加92.55%±8.37%和81.27%±9.95%,其促动力作用与多潘立酮相同.离体实验:①灌流多巴胺(40 mg/ml)可明显抑制离体结肠肌条收缩活动,较Krebs-Ringer液对照组减少91.56%±10.24%.②多潘立酮可阻断多巴胺对离体结肠肌条的舒张作用.结论 多潘立酮可明显增强结肠动力,其作用明显优于莫沙必利,并与西沙必利作用相同.多潘立酮增强结肠动力作用是通过抗多巴胺作用实现.     

胰岛素抵抗血压大鼠血管舒张功能异常的机制

目的 探讨胰岛素抵抗高血压（ＩＲＨ）大鼠血管舒张功能的改变及其可能机制。方法 采用离体血管功能实验方法,在鼠主动脉的舒张功能有其平滑肌钙代谢功能;应用逆转 录多聚酶链反应技术检测主动脉平滑肌Ｃａ＾２＋－ＡＴＰ酶ｍＲＮＡ的表达水平,结果 （１）ＩＲＨ大鼠主动脉舒张速度减慢;（２）用无钙ｋｒｅｂｓ液灌流后苯肾上腺素引起的收缩反应显著低于对照大鼠;（３）ＩＲＨ大鼠主动脉平滑肌Ｃａ＾２＋－ＡＴＰ酶ｍＲＡＮ     

葛根素对大鼠离体肠道平滑肌运动的影响及其机制

目的 探讨葛根素对大鼠离体肠道平滑肌收缩活动的影响及其作用机制.方法 应用PowerLab信号处理仪观察葛根素对大鼠离体肠道平滑肌收缩活动的影响及诱导型NO合酶(iNOS)是否介导葛根素对肠道平滑肌的作用;应用NO试剂盒测定葛根素对结肠内NO含量的影响;应用Western印迹观察葛根素是否上调结肠中iNOS的含量.结果 0.12、0.24、0.48 g/L葛根素对各段肠道平滑肌运动都有明显抑制作用,并随浓度增加而加强.应用SMT(iNOS抑制剂)对结肠平滑肌预处理后再加入葛根素,其对平滑肌作用减弱.0.12、0.24、0.48 g/L葛根素都可提高结肠平滑肌内NO和iNOS含量.结论 葛根素可抑制肠道平滑肌的收缩活动,其机制可能与肠内iNOS表达上调有关.     

白芍总甙对豚鼠结肠平滑肌作用机制的研究

目的 :探讨白芍总甙 (TGP)对离体豚鼠结肠平滑肌的作用方式及对结肠平滑肌中 P物质 (SP)和血管活性肠肽 (VIP)释放的影响。方法 :观察不同剂量 TGP及工具药对离体结肠肌收缩活性的效应及利用 SABC法检测结肠平滑肌中 SP和血管 VIP的变化。结果 :TGP使豚鼠结肠离体平滑肌收缩积分和时间显著性增加 ,且收缩效应的改变具有剂量依赖性。平滑肌中 SP的反应显著性增强。结论 :TGP可通过延长结肠收缩时间 ,增强结肠收缩幅度而调节结肠运动 ,SP是 TGP作用的递质之一。     

急性束缚应激对大鼠结肠敏感性的影响

背景:内脏高敏感性是肠易激综合征(IBS)重要的病理生理特征,而应激事件能诱发或加重IBS患者的症状。目的:了解急性束缚应激对大鼠结肠敏感性的影响和持续时间,以及对单个平滑肌细胞收缩活动的影响。方法:建立急性部分束缚应激大鼠动物模型,于0天(应激前1天)、1天(应激当天)、2天(应激后1天)行结直肠气囊扩张．并行腹壁回撤反射(AWR)评分;分离平滑肌细胞,测定结肠平滑肌细胞的收缩百分率。结果:20 mm Hg和40 mm Hg扩张压力下,束缚组1天的AWR评分显著高于对照组(1．68±0．79对0．81±0．42、2．45±0．72对1．58±0．60,P<0．05);束缚组大鼠1天时AWR评分在20 mm Hg(P1=0．001;P3=0．006)和40 mm Hg(P2=0．012,P4=0．033)扩张压力下与0天、 2天相比显著增加,但在60 mm Hg和80 mm Hg扩张压力下以及对照组在每天的评分均无显著差异;束缚组结肠平滑肌细胞的收缩百分率与对照组无显著差异(P=0．523)。结论:急性束缚应激使大鼠结肠对低压力球囊扩张的敏感性呈一过性增加,对大鼠单个平滑肌细胞的收缩活动没有影响。     

Increase in neurokinin-1 receptor-mediated colonic motor response in a rat model of irritable bowel syndrome

AIM: Irritable bowel syndrome (IBS) is a functional bowel disorder. Its major symptom is bowel dysmotility, yet the mechanism of the symptom is poorly understood. Since the neurokinin-1 receptor (NK1R)-mediated signaling in the gut is important in the control of normal bowel motor function, we aimed to investigate whether the NK1R-mediated bowel motor function was altered in IBS, using a rat IBS model that was previously reported to show colonic dysmotility in response to restraint stress. METHODS: IBS symptoms were produced in male Sprague-Dawley rats by inducing colitis with acetic acid. Rats were left to recover from colitis for 6 d, and used for experiments 7 d post-induction of colitis. Motor activities of distal colon were recorded in vitro. RESULTS: The contractile sensitivity of isolated colon to a NK1R agonist [Sar9,Met(O2)11]-substance P (1-30 nmol/L) was higher in IBS rats than that in normal rats. After the enteric neurotransmission was blocked by tetrodotoxin (TTX, 1 μmol/L), the contractile sensitivity to the NK1R agonist was increased in normal colon but not in IBS rat colon. The NK1R agonist-induced contraction was not different between the two groups when the agonist was challenged to the TTX-treated colon or the isolated colonic myocytes. A nitric oxide synthase inhibitor Nω-nitro-L-arginine methyl ester (L-NAME, 100 μmol/L) augmented the NK1R agonist-induced contraction only in normal rat colon. CONCLUSION: These results suggest that the NK1R-meidated colonic motor response is increased in IBS rats, due to the decrease in the nitrergic inhibitory neural component.     

Effect of pinaverium bromide on stress-induced colonic smooth muscle contractility disorder in rats

AIM: To investigate the effect of pinaverium bromide, a L-type calcium channel blocker with selectivity for the gastrointestinal tract on contractile activity of colonic circular smooth muscle in normal or cold-restraint stressed rats and its possible mechanism. METHODS: Cold-restraint stress was conducted on rats to increase fecal pellets output. Each isolated colonic circular muscle strip was suspended in a tissue chamber containing warm oxygenated Tyrode-Ringer solution. The contractile response to ACh or KCl was measured isometrically on ink-writing recorder. Incubated muscle in different concentrations of pinaverium and the effects of pinaverium were investigated on ACh or KCl-induced contraction. Colon smooth muscle cells were cultured from rats and (Ca(2+))(i) was measured in cell suspension using the Ca(2+) fluorescent dye fura-2/AM. RESULTS: During stress, rats fecal pellet output increased 61 % (P<0.01). Stimulated with ACh or KCl, the muscle contractility was higher in stress than that in control. Pinaverium inhibited the increment of (Ca(2+))(i) and the muscle contraction in response to ACh or KCl in a dose dependent manner. A significant inhibition of pinaverium to ACh or KCl induced (Ca(2+))(i) increment was observed at 10(-6) mol/L. The IC(50) values for inhibition of ACh induced contraction for the stress and control group were 1.66X10(-6) mol/L and 0.91X10(-6) mol/L, respectively. The IC(50) values for inhibition of KCl induced contraction for the stress and control group were 8.13X10(-7) mol/L and 3.80X10(-7) mol/L, respectively. CONCLUSION: Increase in (Ca(2+))(i) of smooth muscle cells is directly related to the generation of contraction force in colon. L-type Ca(2+) channels represent the main route of Ca(2+) entry. Pinaverium inhibits the calcium influx through L-type channels; decreases the contractile response to many kinds of agonists and regulates the stress-induced colon hypermotility.     

Calcium dependence of neurotensin stimulation of circular colonic muscle of the rabbit

The effect of neurotensin on smooth muscle contraction was compared in strips from rabbit proximal and distal circular colonic muscle. The effective dose for neurotensin stimulation that caused a 50% response in both tissues was similar (1.3 X 10(-10) M). The maximal isometric stress, however, was greater in the distal colon than in the proximal colon (p less than 0.01). Neurotensin stimulation of both proximal and distal colon was unaffected by tetrodotoxin, phentolamine, propranolol, naloxone, or atropine. Neurotensin-stimulated contraction was inhibited by "Ca2+-free" (pCa = 5.1) or La3+ buffer. Verapamil (10(-6) M) or nitroprusside (10(-4) M) decreased neurotensin stimulation of proximal and distal colon by approximately 40% (p less than 0.05). Removal of Ca2+ from the buffer inhibited stimulation of muscle contraction by high extracellular potassium [( K+]o) more than bethanechol stimulation (p less than 0.01). La3+ (1 mM) inhibited the contraction stimulated by bethanechol or increased [K+]o. Although verapamil inhibited contraction by bethanechol and increased [K+]o by approximately 50%, nitroprusside had no effect on the contraction mediated by these stimulants. 8-Bromo-guanosine 3',5'-cyclic monophosphate (cGMP) inhibited neurotensin, but not [K+]o or bethanechol-stimulated contraction. These data suggest (a) neurotensin stimulated colonic contractions at a concentration that is potentially physiologic, (b) neurotensin stimulated colonic smooth muscle directly without neural mediation, (c) neurotensin stimulation of colonic muscle is controlled by [Ca2+]o and [cGMP]i.     

Tong Xie Yao Fang relieves irritable bowel syndrome in rats via mechanisms involving regulation of 5-hydroxytryptamine and substance P

AIM: To investigate whether the Chinese medicine Tong Xie Yao Fang (TXYF) improves dysfunction in an irritable bowel syndrome (IBS) rat model.METHODS: Thirty baby rats for IBS modeling were separated from mother rats (1 h per day) from days 8 to 21, and the rectum was expanded by angioplasty from days 8 to 12. Ten normal rats were used as normal controls. We examined the effects of TXYF on defection frequency, colonic transit function and smooth muscle contraction, and the expression of 5-hydroxytryptamine (5-HT) and substance P (SP) in colonic and hypothalamus tissues by Western blot and RT-PCT techniques in both normal rats and IBS model rats with characterized visceral hypersensitivity.RESULTS: Defecation frequency was 1.8 ± 1.03 in normal rats and 4.5 ± 1.58 in IBS model rats (P < 0.001). However, the defecation frequency was significantly decreased (3.0 ± 1.25 vs 4.5 ± 1.58, P < 0.05), while the time (in seconds) of colon transit function was significantly increased (256.88 ± 20.32 vs 93.36 ± 17.28, P < 0.001) in IBS + TXYF group rats than in IBS group rats. Increased colonic smooth muscle tension and contract frequency in IBS model rats were significantly decreased by administration of TXYF. Exogenous agonist stimulants increased spontaneous activity and elicited contractions of colon smooth muscle in IBS model rats, and all of these actions were significantly reduced by TXYF involving 5-HT and SP down-regulation.CONCLUSION: TXYF can modulate the activity of the enteric nervous system and alter 5-HT and SP activities, which may contribute to the symptoms of IBS.     

Signal pathways involved in emodin-induced contraction of smooth muscle cells from rat colon

AIM: To investigate the effects induced by emodin on single smooth muscle cells from rat colon in vitro, and to determine the signal pathways involved.METHODS: Cells were isolated from the muscle layers of Wistar rat colon by enzymatic digestion. Cell length was measured by computerized image micrometry. Intracellular Ca^2+ ([Ca^2+]i) signals were studied using the fluorescent Ca^2+ indicator fluo-3 and confocal microscopy. PKCα distribution at rest state or after stimulation was measured with immunofluorescence confocal microscopy.RESULTS: (1) Emodin dose-dependently caused colonic smooth muscle cells contraction, (2) emodin induced an increase in intracellular Ca^2+ concentration; (3) the contractile responses induced by emodin were respectively inhibited by preincubation of the cells with ML-7 (an inhibitor of MLCK) and calphostin C (an inhibitor of PKC), (4) Incubation of cells with emodin caused translocation of PKCα from cytosolic area to the membrane.CONCLUSION: Emodin has a direct contractile effect on colonic smooth muscle cell. This signal cascade induced by emodin is initiated by increased [Ca^2+]i and PKCα translocation,which in turn lead to the activation of MLCK and the suppression of MLCP. Both of them contribute to the emodininduced contraction.     

Inhibition of acetylcholine induced intestinal motility by interleukin 1 beta in the rat.

BACKGROUND/AIMS: The fact that raised interleukin 1 beta (IL 1 beta) concentrations have been found in the colonic mucosa of rats with experimentally induced colitis and of patients with inflammatory bowel disease indicates that this cytokine may participate in the disturbed intestinal motility seen during inflammatory bowel disease. This study investigated whether IL 1 beta could change the contractility of (a) a longitudinal muscle-myenteric plexus preparation from rat jejunum, ileum, and colon and (b) isolated jejunal smooth muscle cells. METHODS: Isometric mechanical activity of intestinal segments was recorded using a force transducer. Moreover, smooth muscle cell length was measured by image analysis. RESULTS: Although IL 1 beta did not affect jejunal, ileal, and colonic basal contractility, it significantly reduced contractile response to acetylcholine (ACh). This significant inhibition was seen only after 90 or 150 minutes of incubation with IL 1 beta. Pretreatment with cycloheximide blocked IL 1 beta induced inhibition of ACh stimulated jejunal contraction, suggesting that a newly synthesised protein was involved in the effect. NW-nitro-L-arginine (a nitric oxide synthase inhibitor) did not prevent the inhibition induced by IL 1 beta. Blocking neural transmission with tetrodotoxin abolished the IL 1 beta effect on jejunal contractile activity, whereas IL 1 beta had no effect on isolated and dispersed smooth muscle cells. CONCLUSIONS: IL 1 beta inhibits ACh induced intestinal contraction and this inhibitory effect involves protein synthesis but is independent of nitric oxide synthesis. This effect does not involve a myogenic mechanism but is mediated through the myenteric plexus.     

Sources of calcium in neurokinin A–induced contractions of human colonic smooth muscle in vitro

OBJECTIVES: Tachykinins have been implicated in the pathogenesis of colonic dysmotility. The sources of activator calcium for neurokinin A (NKA)-induced contraction of human colonic smooth muscle have not been assessed. We evaluated the contribution of extracellular and intracellular Ca2+ to NKA-induced contractions. METHODS: Circular smooth muscle strips of human colon were suspended under 1 g of tension in organ baths containing Krebs solution at 37 degrees C gased with 95% O2/5% CO2. Contractile activity was recorded isometrically. RESULTS: Cumulatively applied NKA (0.1 nmol/L-0.3 micromol/L), produced concentration-dependent contractions of human colonic smooth muscle strips that were not affected by tetrodotoxin (1 micromol/L). The contractile response to NKA was abolished in a Ca2+-free medium containing ethylenediaminetetraacetate (EDTA) (1 mmol/L). Pretreatment of muscle strips with nifedipine (1 micromol/L), an L-type voltage-operated Ca2+ channel antagonist, abolished the contractile responses to NKA. Pretreatment with SK&F 96365 (10 micromol/L and 30 micromol/L), a putative receptor-activated and voltage-operated Ca2+ channel antagonist, attenuated the contractile responses. Depletion of intracellular Ca2+ stores with thapsigargin (1 micromol/L), an inhibitor of the sarcoplasmic reticulum Ca2+ ATP-ase, had no effect on NKA-induced contractions. CONCLUSIONS: NKA-mediated contraction of human colonic smooth muscle is dependent on an influx of extracellular Ca2+ through L-type voltage-operated Ca2+ channels. Intracellular Ca2+ release seems to have little role to play in NKA-mediated contractions.