血糖浓度变化与消化间期综合肌电周期的关系

在狗的十二指肠浆膜面埋植银-氯化银双极电极,记录空腹时的肌电活动,观察血糖浓度变化与消化间期综合肌电(IDMEC)周期的关系。实验结果表明:(1)血糖浓度随 IDMEC周期的不同时相而变动,Ⅰ相最高,Ⅱ相次之,Ⅲ相最低(P<0.01)。(2)静脉注射酚妥拉明或心得安后。血糖浓度随 IDMEC 周期的波动均消失。(3)切除双侧迷走神经干后,血糖浓度略有升高,随 IDMEC 的周期性波动依然存在。(4)分别阻断肾上腺素α、β受体及切除迷走神经后,不影响 IDMEC 的周期性活动,但可使周期延长,各相所占时程百分比发生变化。以上结果证明,空腹情况下血糖浓度随 IDMEC 周期的不同时相而变动,交感神经和迷走神经具有一定的调节作用。     

血浆游离脂肪酸浓度变化与消化间期综合肌电周期的关系

用狗进行慢性实验,在十二指肠浆膜缝植三对双极电极,记录空腹时的电活动。观察血浆游离脂肪酸(FFA)浓度变化与消化间期综合肌电(IDMEC)周期性活动的关系。实验结果提示:(1)血浆FFA浓度随IDMEC周期不同时相而变动,Ⅰ相时最低,Ⅲ相时最高(P<0.01);(2)静脉注射心得安后,血浆FFA浓度降低,随IDMEC的周期波动消失;(3)静脉注射酚妥拉明后,在IDMEC的各时相中血浆FFA浓度升高,且无周期性波动;(4)切除双侧迷走神经干后,血浆FFA浓度略有降低,随IDMEC的周期波动仍然存在;(5)静脉注射心得安、酚妥拉明和切除迷走神经后,对IDMEC的周期性活动没有明显的影响。以上结果证明,在空腹情况下血浆FFA浓度随IDMEC周期的不同时相而变动,交感神经系统在这些变动中具有一定的作用。     

巴豆油所致的腹泻过程中狗小肠电活动的改变

在14只狗小肠浆膜面埋植Ag-AgCl双极电极,以消化间期综合肌电(IDMEC)为指标,经胃管向胃内注入10％巴豆油。结果如下:(1)巴豆油注入胃内后,即诱发一起源于十二指肠、沿小肠向其尾端移行、持续时间比正常IDMECⅢ相短(p<0.01)、而传导速度却较正常Ⅲ相快(p<0.01)的类Ⅲ相。(2)巴豆油注入胃内后,正常IDMEC周期即被中断117～234min不等。与正常IDMEC周期相比,恢复后IDMEC周期缩短(p<0.05)。(3)分别阻断α与β受休后,巴豆油胃内注入所诱发的类Ⅲ相及对IDMEC周期的影响均与单纯胃内注入巴豆油所引起的改变相似。双侧膈上迷走神经切除后,巴豆油仍能诱发类Ⅲ相,但其出现的潜伏时间明显延长(p<0.001),并在384.9±75.3min内未见IDMEc周期恢复。结果提示:巴豆油胃内注入所诱发的类Ⅲ相及对IDMEC周期的影响与α和β受体无关。迷走神经起一定的调节作用。巴豆油胃内注入所诱发的类Ⅲ相及所引起的IDMEC周期缩短可能是导致腹泻发生的原因之一。     

狗小肠部分切除对移行性综合肌电的影响

将9只狗的小肠总长度的30％,50％及75％的上端分别切除,观察其对移行性综合肌电(MMC)发生规律和红霉素诱发MMCⅢ相的影响。结果发现,所有小肠部分切除的狗,残余小肠的慢波节律均较小肠完整时相应部位明显减慢;75％上端小肠切除的狗,MMC活动消失。小肠完整的狗,静脉注射红霉素均能使MMCⅢ相提前发生;30％上端小肠切除的狗,红霉素仅在一半的实验中可诱发MMCⅢ相,50％及75％上端切除后,红霉素不能诱发MMCⅢ相。但静脉注射吗啡后在所有动物模型上均能诱发MMCⅢ相。提示小肠MMC的周期活动需要空肠以上小肠的存在,红霉素仅在小肠上端能诱发MMCⅢ相。     

绒毛膜促性腺激素及孕酮对大鼠小肠移行性综合肌电的影响

于去卵巢大鼠小肠的不同部位植入铂金丝单极电极,观察了绒毛膜促性腺激素(HCG)及孕酮对其移行性综合肌电(MMC)的影响。结果为:(1) 静注HCG后,十二指肠及空肠上段出现典型的与妊娠有关的MMC改变,即MMC的周期被间断出现且不规则延长的Ⅱ相所打乱。(2) 肌注孕酮后,十二指肠MMC的Ⅰ相和Ⅱ相时程均显著延长,但MMC的周期性无明显紊乱。(3) 在肌注孕酮的基础上加注HCG后,MMC的变化在特征上与单独注射HCG时相同,在范围上扩大到整个小肠。上述结果提示,在大鼠,HCG可引起典型的与妊娠有关的MMC活动紊乱;当有孕酮存在时,HCG的这一效应进一步增强。     

PGE1对大鼠在体小肠肌电活动的影响

PGEs exhibit a variety of actions on gastrointestinal motility.The study,therefore,has been performed to determine the effect of PGE1 on conscious rats intestinal myoelectric activity and the relation of the PGE1 action with cholinergic M receptor and adrenergic α and β receptors.     

兔迷走复合区内微量注射TRH对奥迪氏括约肌肌电的影响及？…

目的和方法：本工作旨在研究兔迷走复合区（ＤＶＣ）内ＴＲＨ对奥迪氏括约肌电的调节作用及外周途径。结果：（１）ＤＶＣ内注射ＴＲＨ（０．８ｎｍｏｌ,μｌ）后,慢波电位（ＳＷ）频率不变,但锋电位频率（ＦＳＰＳＯ）及幅度（ＡＳＰ－ＳＯ）,锋电位发生率（ＩＳＰ）明显增加。（２）ＤＶＣ内分别注射不同剂量ＴＲＨ（０．１３,０．２５,０．５０,０．８０,１．３０ｎｍｏｌ,１μｌ）后,各剂量ＴＲＨ均能引起ＦＳＰＳＯ增     

胃肠道的消化间期综合肌电

胃肠道的消化间期综合肌电作为其平滑肌活动的主要指标是近年来比较活跃的研究领域,这种肌电是指在空腹、清醒情况下,反复发生于胃肠道并能向小肠下端缓慢扩布或秽行的周期性综合电变化,具有明显的时相性特征,能规律地从胃、十二指肠和空肠上部开始,向下扩布到回肠末端。消化间期综合肌电各时相的产生,与血浆中胃动素浓度周期性变化的水平有一定的依从关系。植物神经系统和胃肠道的一些激素以及进食,都能影响这种综合肌电,但切除外来神经后,一般都不能使这种综合肌电的规律活动完全消失。     

脑室和静脉注射吗啡对狗移行性综合肌电的影响

用10只狗作慢性实验,沿胃窦、小肠缝植8对银-氯化银双极电极,观察脑室和静脉注射吗啡对移行性综合肌电(migrating myoelectric complex,MMC)的影响。结果:(1)在十二指肠MMC周期时程的43％以后,静脉注射吗啡能诱发MMCⅢ相活动提前发生;在42％以内则无效应。(2)静脉注射3,000μg吗啡后,MMC周期延长,胃窦慢波频率减少;静脉注射300μg吗啡,对MMC周期时程和胃窦慢波频率无影响。(3 )脑室注射吗啡后,胃、小肠慢波首先发生自下而上的逆行性抑制,随之各部位峰电活动增多,十二指肠还发生痉挛性收缩的峰电活动,动物伴有呕吐的前驱症状和呕吐,MMC周期延长,胃窦慢波频率减少。(4)切断双侧膈上迷走神经后,脑室注射吗啡对胃和小肠肌电活动影响消失,但呕吐及其前驱症状仍然发生。     

女子拳击运动员上肢和腰部肌肉力量训练的肌电分析

目的：利用肌电指标分析拳击运动员上肢和腰部肌肉力量训练效果。方法：用Mega公司的ME6000肌电图仪记录分析10名女子拳击运动员上臂肱二头肌（主动肌）与肱三头肌（拮抗肌）、前臂屈肌（主动肌）与伸肌（拮抗肌）和腰部肌群的运动诱发肌电,规定运动为手持2.5 kg的哑铃负荷进行直拳空击运动直至局部肌肉力竭。结果：直拳空击运动至局部肌肉力竭过程中,上肢拮抗肌的中位频率（MF）下降幅度和速度大于相对应的主动肌,且从肌群作功来看,主动肌作功百分比较拮抗肌大。其中9名普通运动员腰肌的肌电频率（MF）均值较1名指定样本世界冠军的下降缓慢,而且其作功百分比都较小。结论：通过对普通女子拳击运动员上肢和腰部肌群肌电指标测试与世界冠军的比较分析,提示本研究中所测普通拳击运动员拮抗肌和腰部肌肉力量训练不足,有待加强该部肌肉的力量训练。     

Superoxide Dismutase (SOD) and the Paf-Antagonist (BN 52021) Reduce Small Intestinal Damage Induced by Ischemia-Reperfusion

Oxygenated free-radicals appear to play a prominent role in mediating damage associated with gastrointestinal diseases. Production of reactive oxygen metabolites in ischemia-reperfusion involves oxidases found in resident phagocytic cells and microvascularand mucosal epithelial cells. Platelet activating factor (PAF), a phospholipid associated with inflammatory disorders, has been shown to both prime and amplify the release of superoxide anion and hydrogen peroxide from polymorphonuclear neutrophils and macrophages stimulated by FMLP or PMA. To further elucidate the involvement of free radicals in intestinal damage and the potential role of PAF in their production, we examined the effect of superoxide dismutase (SOD) and BN 52021 (ginkgolide B) on ischemia-reperfusion induced damage in the small intestine.

The study involved 32 Sprague-Dawley rats (100–200 g) divided into four groups. Three of these groups were subjected to occlusion of the mesenteric artery 30 mins followed by 24 h reperfusion. On 2 groups SOD (15,000 U/kg/iv) and BN 52021 (20 mg/kg/po) were administered 45 mins before arterial occlusion. Following the 24 h reperfusion, the rats were sacrificed after overnight fasting. The jejunum and ileon were removed and fixed for morphological examination. Lesions in the small intestine were quantified.

The results showed extensive necrosis, hemorrhage, oedema and neutrophil invasion in the jejunal and ileal mucosa. This injury was significantly reduced by SOD (15.000 U/kg/iv) and BN 52021 (20 mg/kg/po) pretreatment. In conclusion, free-oxygenated radicals appear to mediate reperfusion damage in the small intestine and PAF appears to be involved in the genesis of these toxic products. Thus, SOD and BN 52021 may be considered as protectors against ischemic disorders.     

Thiocyanate transport across fish intestine (Pleuronectes platessa)

Summary When bathed on both sides with identical chloride-containing salines thein vitro preparation of the plaice intestine maintains a negative (serosa to mucosa) short-circuit current of 107±11 A/cm², a transepithelial potential difference of 5.5±0.6 mV (serosa negative), and a mean mucosal membrane potential of –45.4±0.6 mV. Under these conditions the intracellular chloride activity is 32mm.If chloride in the bathing media is partially, or completely substituted by thiocyanate the measured electrical parameters do not change but transepithelial flux determinations show a reduction in chloride fluxes and the presence of a significant thiocyanate flux. The addition of piretanide (10^–4 m) reduced the short-circuit current and the mucosa-to-serosa fluxes of chloride and thiocyanate; this inhibition is similar to the effect of piretanide on chloride transport in this tissue.The results indicate that thiocyanate is transported in this tissue via the piretanide-sensitive chloride pathway and are compared with the effects of thiocyanate on other tissues reported in the literature.     

Phylogeny of trichostome ciliates (Ciliophora, Litostomatea) endosymbiotic in the Yakut horse (Equus caballus)

Ciliates of the subclass Trichostomatia inhabit the fermentative regions of the digestive tract of herbivores. Most available small subunit ribosomal RNA (SSrRNA) gene sequences of trichostomes are from species isolated from the rumen of cattle or sheep and from marsupials. No ciliate species endosymbiotic in horses has yet been analyzed. We have sequenced the SSrRNA genes of five ciliate species, isolated from the cecum and colon of four Yakut horses: Cycloposthium edentatum, Cycloposthium ishikawai, Tripalmaria dogieli, Cochliatoxum periachtum, and Paraisotricha colpoidea.

Based on their morphology, Cycloposthium, Tripalmaria, and Cochliatoxum are classified as Entodiniomorphida, while Paraisotricha is considered a member of the Vestibuliferida. Phylogenetic analyses using Bayesian inference, distance, and parsimony methods confirm these placements. The two Cycloposthium species cluster together with the published Cycloposthium species isolated from a wallaby in Australia. Tripalmaria and Cochliatoxum branch as a sister group to or basal within the Entodiniomorphida. The Vestibuliferida remain paraphyletic with Paraisotricha and Balantidium branching basal to all other trichostome species, but not closely related to Isotricha and Dasytricha.     

The Development of Trypanosoma cruzi (Trypanosomatidae) in the Reduviid Bug Triatoma infestans (Insecta): Influence of Starvation

ABSTRACT Fifth instars of Triatoma infestans with established Trypanosoma cruzi infections were dissected after different periods of starvation to determine the population density and the percentage of different developmental stages of T. cruzi in the small intestine and rectum of the bugs. After a short starvation period of 20 days, the population density in the small intestine was 20% (about 60,000) of the rectal population. The population in the small intestine was strongly reduced after an additional ten days of starvation, and no flagellates could be found there 60, 90 and 120 days after the last feeding. In the rectum, this reduction went down to 1% of the initial population, but a total elimination never occurred. Usually the remaining population contained more live than dead flagellates. Starvation also resulted in an increase in the rectum in the number and percentage of drop-like forms, intermediates between sphere- and epi- or trypomastigotes, from 1% initially to about 10% after 90 days of starvation. The percentage of spheromastigotes increased from 2% at 20 days after the last feeding to about 20% after an additional 40 and 70 days. Therefore, the spheromastigotes of T. cruzi seem to be induced by stress conditions.     

Immunolocalization of EGF receptor (EGFr) in intestinal epithelium: recognition of apoptotic cells

The EGF-like family of growth factors are known to be involved in the control of the intestinal epithelium. The intracellular events are mediated by the EGF receptor (EGFr), a transmembrane glycoprotein which is overexpressed in many malignancies and also in many radiosensitive cell types. The precise mode of action of the receptor in controlling proliferation and whether the factor is also involved in controlling apoptosis in this tissue is not clear. Using polyclonal antibodies raised against a cytoplasmic region of the receptor distant to the phosphorylation site and one raised against the peptide sequence DVVDADEYLIPQ, which is present in the cytoplasmic tail phosphorylation site of the EGFr, we have examined the immunostaining in normal and irradiated murine intestine. The former antibody labelled the basolateral membranes of the epithelial cells in the proliferative zones of both the small intestine and colon, in both control and irradiated tissue. The latter antibody however, strongly labelled the Goblet cells and the microvilli of the enterocyte apical membrane in control tissue. Following irradiation\ the apical labelling redistributed and was localized in the apical cytoplasm and in a paranuclear region. Furthermore, strong labelling was now seen in many of the apoptotic cells of the small intestinal epithelium. The greatly differing results with the two antibodies indicates that interpretation of such immunostaining must be viewed with caution and may relate to the availability of each particular epitope. These results also suggest that antibodies to DVVDADEYLIPQ may be a useful marker of apoptotic calls and could imply a correlation between high levels of epitope availability, the radiosensitive (frequently p53 expressing) cells of the crypt epithelium and the induction of apoptosis.This work was supported by the Cancer Research Campaign.     

Expression of the monocarboxylate transporter 1 (MCT1) in cells of the porcine intestine

Uptake of energy into cells and its allocation to individual cellular compartments by transporters are essential for tissue homeostasis. The present study gives an analysis of MCT1 expression and its cellular occurrence in the porcine intestine. Tissue portions from duodenum, jejunum, ileum, colon ascendens, colon transversum and colon descendens were collected and prepared for immunohistochemistry, Western blot and real time RT-PCR. A 169bp porcine MCT1 cDNA fragment was amplified and published. MCT1 mRNA expression in the large intestine was 20 fold higher compared to the small intestine. Western blot detected a single protein band of 41kDa at a much higher amount of MCT1 protein in the large intestine vs. the small intestine. MCT1 protein was detected in mitochondrial fractions of the large but not the small intestine. Immunohistochemistry in the small intestine showed that immune cells in the lamina propria and in the lymphoid follicles primarily expressed MCT1 while in the colon epithelial cells were the main source of MCT1. In summary, cellular expression of MCT1 differs between epithelial cells in the colon and small intestine. A possible role of MCT1 for uptake of butyrate into immune cells and the overall role of MCT1 for intestinal immune cell function remains elusive.     

Na-H Exchanger Isoform-2 (NHE2) Mediates Butyrate-dependent Na+ Absorption in Dextran Sulfate Sodium (DSS)-induced Colitis

Diarrhea associated with ulcerative colitis (UC) occurs primarily as a result of reduced Na⁺ absorption. Although colonic Na⁺ absorption is mediated by both epithelial Na⁺ channels (ENaC) and Na-H exchangers (NHE), inhibition of NHE-mediated Na⁺ absorption is the primary cause of diarrhea in UC. As there are conflicting observations reported on NHE expression in human UC, the present study was initiated to identify whether NHE isoforms (NHE2 and NHE3) expression is altered and how Na⁺ absorption is regulated in DSS-induced inflammation in rat colon, a model that has been used to study UC. Western blot analyses indicate that neither NHE2 nor NHE3 expression is altered in apical membranes of inflamed colon. Na⁺ fluxes measured in vitro under voltage clamp conditions in controls demonstrate that both HCO₃⁻-dependent and butyrate-dependent Na⁺ absorption are inhibited by S3226 (NHE3-inhibitor), but not by HOE694 (NHE2-inhibitor) in normal animals. In contrast, in DSS-induced inflammation, butyrate-, but not HCO₃⁻-dependent Na⁺ absorption is present and is inhibited by HOE694, but not by S3226. These observations indicate that in normal colon NHE3 mediates both HCO₃⁻-dependent and butyrate-dependent Na⁺ absorption, whereas DSS-induced inflammation activates NHE2, which mediates butyrate-dependent (but not HCO₃⁻-dependent) Na⁺ absorption. In in vivo loop studies HCO₃⁻-Ringer and butyrate-Ringer exhibit similar rates of water absorption in normal rats, whereas in DSS-induced inflammation luminal butyrate-Ringer reversed water secretion observed with HCO₃⁻-Ringer to fluid absorption. Lumen butyrate-Ringer incubation activated NHE3-mediated Na⁺ absorption in DSS-induced colitis. These observations suggest that the butyrate activation of NHE2 would be a potential target to control UC-associated diarrhea.