水飞蓟宾在大鼠小肠中的吸收特性

目的考察水飞蓟宾在大鼠各肠段的吸收。方法以一定浓度的水飞蓟宾溶液作为灌流液，以0.1 mL·min^-1进行大鼠不同肠段的单向灌流,于不同时间收集肠灌流液并肝门静脉取血，分别用HPLC测定灌流液和血中药物浓度。结果实验结果表明190 μg·mL^-1水飞蓟宾在不同肠段的吸收速率常数(k_a)和有效透过系数(P_eff)是十二指肠>空肠>回肠>结肠。质量浓度为80 μg·mL^-1的水飞蓟宾灌流液在十二指肠的吸收与190和300 μg·mL^-1的吸收情况均有显著性差异(P<0.05)，但质量浓度为190 μg·mL^-1与300 μg·mL^-1的吸收之间无显著性差异(P>0.05)。肝门静脉血中药物分析也显示十二指肠>空肠>回肠>结肠。结论水飞蓟宾在小肠全肠道均有吸收且有高浓度饱和现象。     

原人参二醇纳米混悬剂的大鼠在体肠吸收研究

目的 考察原人参二醇纳米混悬剂的在体肠吸收特征。方法 采用溶剂蒸发法, 以白蛋白作为稳定剂制备原人参二醇纳米混悬剂。以酚红为标示物, 采用大鼠在体单向肠灌流法评价原人参二醇纳米混悬剂的大鼠在体肠吸收特性。结果 Zetasizer nano ZS仪测得原人参二醇纳米混悬剂平均粒径为(220±10)nm, Zeta电位为(-28±0.2)mV。肠吸收实验表明, 原人参二醇纳米混悬剂在整个肠段都有吸收, 且吸收速率常数(K_a)与渗透系数(P_eff)均大于原人参二醇原药(P<0.05), 原人参二醇纳米混悬剂在小肠段(十二指肠、空肠和回肠)的K_a与P_eff均大于结肠(P<0.05)。结论 原人参二醇纳米混悬剂能够有效促进原人参二醇的大鼠在体肠吸收, 其转运机制可能为主动转运或促进扩散。     

在体单向灌流法研究阿哌沙班肾衰大鼠肠吸收特性

目的 研究阿哌沙班在肾衰大鼠体内的肠吸收特性,并考察P糖蛋白(P-glycoprotein,P-gp)抑制剂对阿哌沙班吸收行为的影响。方法 选择肾衰大鼠在体单向灌流法进行肠吸收实验,建立大鼠阿哌沙班肠灌流液HPLC分析方法,以考察大鼠在体肠吸收影响因素。结果 阿哌沙班在各肠段的吸收速率常数（K_a）存在显著性差异（P<0.05）,但表观吸收系数（P_app）未见明显差异（P>0.05）;大鼠回肠段的K_a和P_app值随药物浓度的增加而降低;加入 P-gp抑制剂盐酸维拉帕米（0.1 mmol/L）后,阿哌沙班在空肠和回肠段的K_a和P_app值均明显增加。结论 阿哌沙班在各肠段均有吸收;P-gp抑制剂对阿哌沙班在空肠和回肠段的吸收均有明显的促进作用,表明阿哌沙班为P-gp底物,推测其吸收机制为主动转运。     

独活有效成分大鼠在体单向灌流肠吸收

为了考察独活提取物中二氢欧山芹醇乙酸酯、蛇床子素、二氢欧山芹醇当归酸酯等3种主要有效成分在大鼠的肠吸收性质,了解中药提纯后对大鼠肠吸收的影响，本文运用单向灌流模型并采用HPLC法测定独活提取物I(总香豆素含量＜10%)灌流液中3种成分在体肠灌流的浓度变化，并与独活提取物II(总香豆素含量≥60%)进行比较。结果表明二氢欧山芹醇乙酸酯、蛇床子素及二氢欧山芹醇当归酸酯的质量浓度分别为62～555 μg·mL^-1、101～887 μg·mL^-1和19～186 μg·mL^-1，吸收量与浓度呈线性关系,无高浓度饱和现象，吸收速率常数(K_a)、吸收渗透系数(P_app)值基本保持不变。3种成分在大鼠小肠主要以被动扩散方式吸收；在各肠段均有吸收，其中结肠吸收最好，各肠段的K_a、 P_app是结肠＞十二指肠＞空肠＞回肠，且结肠的K_a、 P_app值显著大于其他肠段；独活提取物II中3种成分的K_a、 P_app值显著小于独活提取物I中相应成分。     

白头翁皂苷B3的溶解度及油水分配系数与大鼠在体肠吸收研究

目的 测定白头翁皂苷B3的表观溶解度及油水分配系数,并研究其大鼠在体肠吸收机制。方法 HPLC-ELSD法测定B3的表观溶解度和油水分配系数,重量法计算大鼠在体单向肠灌流实验中吸收速率常数(K_a)和表观吸收系数(P_app)。结果 白头翁皂苷B3在37℃有机溶剂中的表观溶解度较低,在碱性磷酸盐缓冲液中的表观溶解度较高;白头翁皂苷B3在不同磷酸盐缓冲液中的油水分配系数相差不大;白头翁皂苷B3在大鼠十二指肠、空肠、回肠和结肠的K_a和P_app没有显著性差异(P > 0.05);白头翁皂苷B3在0.05~2.5 mg/mL随着浓度提高出现过饱和现象;加入P-糖蛋白抑制剂维拉帕米和P-糖蛋白底物地高辛后,都能显著提高白头翁皂苷B3的K_a值。结论 在实验浓度范围内,溶解度和油水分配系数能够较好地预测肠吸收情况;白头翁皂苷B3不完全依赖浓度梯度转运,细胞膜上的载体蛋白参与了药物的转运过程,其小肠吸收机制并不完全为被动转运;受吸收部位影响较小,无特殊的吸收窗;P-糖蛋白介导了白头翁皂苷B3的小肠吸收。     

芍药苷及芍药苷磷脂复合物胶束在体肠吸收对比分析

目的比较芍药苷（PF）和芍药苷磷脂复合物（PF-PLC）胶束的肠吸收特点,探讨磷脂复合物胶束提高PF生物利用度的作用机制。方法采用大鼠在体单向肠灌流模型,以吸收速率常数（Ka）和有效渗透系数（P_eff）为指标,通过超高相液相色谱（UPLC）测定不同浓度PF原料药和PF-PLC胶束在十二指肠中的肠吸收情况。同时,在灌流液中添加维拉帕米,考察P-糖蛋白（P-gp）抑制剂对PF原料药和PF-PLC胶束肠吸收的影响。结果PF-PLC胶束浓度的提高可显著增加PF的肠道吸收（P＜0.001,P＜0.05）。在灌流液中加入维拉帕米后发现,与单纯PF组比较,PF+维拉帕米组的Ka和Peff值虽有增加的趋势,但无明显统计学差异;与PF-PLC胶束组比较,PF-PLC胶束+维拉帕米组差异也无统计学意义。结论大鼠在体单向肠灌流实验结果显示PF-PLC胶束的吸收主要是被动转运途径,且磷脂复合物胶束的形成显著改善了PF在十二指肠的吸收。维拉帕米的加入对PF-PLC胶束的吸收无显著影响,即PF-PLC胶束的吸收不受外排转运体的影响,这可能是生物利用度提高的原因之一。     

响应面法优化西罗莫司胶束及其促小肠吸收作用

目的 制备和优化西罗莫司（sirolimus，SRL）聚合物胶束，考察其对大鼠在体肠吸收动力学的影响。方法 以去氧胆酸修饰的壳聚糖（deoxycholic acid grafted chitosan，CS-DCA）为载体，采用溶剂蒸发法制备SRL CS-DCA胶束。以包封率、载药量、粒径和电位作为考察指标，结合星点设计-效应面法优化处方。建立大鼠在体单向肠灌流模型，并通过肠腔有效吸收系数（P_eff）、吸收速率常数（K_a）和药物吸收剂量分数（f_a）研究不同浓度SRL CS-DCA的肠吸收特性。结果 SRL CS-DCA最优处方：载体浓度（CS-DCA）为10 mg·mL^-1，药物与载体质量比为20%，该条件下制备得到的SRL CS-DCA带正电荷（37.0±2.7）mV，粒径（182.2±5.7）nm，包封率>90%，载药量（15.8±0.5）%。SRL CS-DCA经大鼠全肠后，反映药物肠吸收程度的评价指标P_eff、K_a和f_a均较SRL有显著提高（P<0.05）；不同浓度的SRL CS-DCA在大鼠全肠段的P_eff、K_a、f_a值无显著性差异，提示胶束在10~100 μg·mL^-1吸收无浓度抑制，吸收特征为被动转运的线性动力学过程，推测其可能的吸收机制为被动扩散。结论 SRL制备成聚合物胶束后，对其在大鼠小肠的吸收具有明显的促进作用，从侧面证明SRL CS-DCA能有效改善SRL口服生物利用度。     

柚皮素、橙皮素的大鼠在体肠吸收特性研究

目的 考察柚皮素、橙皮素在大鼠肠道的吸收特性,并考察P-糖蛋白(P-gp)对这2种成分吸收的影响。方法 采用大鼠在体肠灌流模型,以超高效液相色谱(UPLC)测定灌流液中柚皮素、橙皮素的含量,计算有效渗透系数(P_eff*)及10 cm肠段吸收百分比。结果 20 μmol·L^-1柚皮素在十二指肠、空肠、回肠、结肠4个肠段的P_eff*值分别为2.77±0.43,2.39±0.30,1.90±0.53,3.15±0.30;20 μmol·L^-1橙皮素分别为2.51±0.18,2.29±0.12,1.99±0.14,3.38±0.20。当两者加了P-gp抑制剂维拉帕米后,柚皮素、橙皮素在4个肠段的吸收均显著增加(P<0.05)。结论 柚皮素、橙皮素在大鼠肠道内吸收较好,但两者均可被肠黏膜上的P-gp外排。     

在体单向肠灌流模型研究小檗碱及其在复方配伍环境中的大鼠肠吸收特性

本实验主要考察药物浓度、肠段、pH、P-糖蛋白 (P-glycoprotein, P-gp) 及Na⁺依赖型葡萄糖转运体 (Na⁺-dependent glucose transporter, SGLT1) 对小檗碱肠吸收的影响, 并探索复方配伍环境中小檗碱的肠吸收情况。实验以酚红为标示物, 采用大鼠在体单向肠灌流模型, 运用高效液相色谱法考察小檗碱单体 (36.70、46.17和92.33 μg·mL⁻¹)、黄连解毒汤模拟体系 (主要指标成分单体混合物: 小檗碱 + 黄芩苷 + 栀子苷, 其中小檗碱浓度为92.33 μg·mL⁻¹) 及黄连解毒汤全方 (小檗碱浓度为92.33 μg·mL⁻¹) 中小檗碱在大鼠各肠段的吸收变化情况。结果表明: 小檗碱在一定浓度范围内 (20～100 μg·mL⁻¹), 部分大鼠小肠吸收速率参数 (K_a) 无显著性差异, 提示药物的吸收机制可能为被动扩散, 其转运过程可能受SGLT1和P-gp的影响; 单体混合物和全方中小檗碱在各肠段的K_a和有效渗透系数 (P_eff) 值均有显著性增加 (P < 0.05)。说明小檗碱在整个肠段均有吸收, 具有广泛的吸收窗, 其中结肠段吸收较好; 配伍对小檗碱的大鼠肠吸收特性有一定影响, 较单体而言, 单体混合物和全方灌流时小檗碱在小肠中吸收更好。     

磷脂对甘草酸二铵小肠吸收的影响

研究磷脂对甘草酸二铵及甘草次酸小肠吸收的影响。建立大鼠原位单向肠灌流及伴有肠系膜插管的肠灌流模型，采用高效液相色谱法检测灌流液及血浆中的药物浓度，计算表观通透系数P_app和吸收速率常数K_a。建立大鼠灌胃后肝门静脉取血模型，测定门静脉血浆中药物浓度，以对灌流结果进一步验证。甘草酸二铵和甘草次酸均能跨肠壁吸收，其P_app分别为0.36和5.73 cm·min^-1，加入磷脂后，P_app分别提高到0.68和7.98 cm·min^-1。磷脂使甘草酸二铵本身的吸收略有增加，但统计学检验差异不显著，但对其肠道菌群代谢物甘草次酸的吸收有显著促进作用。     

Gastrointestinal Transit and Distribution of Ranitidine in the Rat

Purpose. Ranitidine gastrointestinal distribution was examined in the rat small intestine after oral administration to determine whether intestinal transit or secretion (exsorption) may influence the appearance of secondary peaks in ranitidine serum concentration-time profiles. Methods. Male Sprague-Dawley rats received ranitidine (50 mg/kg) by oral gavage, and the mass of ranitidine recovered in all small intestinal segments (~12 cm each) was determined 30, 60, 90, or 120 min after administration. In a separate group of anesthetized rats, the small intestine was divided into two segments of equal length that were perfused with normal saline in a single-pass manner. Rats received an escalating, zero-order IV infusion of ranitidine for 30 min, and venous blood and intestinal effluent were collected over 90 min to quantitate ranitidine exsorption. Results. Thirty min after oral administration, >50% of the recovered ranitidine mass resided in the lower half of the small intestine in all rats. Ranitidine mass in 5 of 16 rats displayed a bimodal distribution with significant amounts of ranitidine recovered from the stomach 60 to 90 min after dosing. Ranitidine exsorption was more efficient from the lower jejunum and ileum than from the duodenum and upper jejunum. However, intestinal secretion of ranitidine was minor (5% of the IV dose). Conclusions. Ranitidine absorption from the lower ileum contributes significantly to systemic ranitidine concentrations before and during the time of the first concentration maximum. Separation of the drug mass into multiple boluses may contribute to secondary peaks in ranitidine concentration-time profiles. Exsorption did not contribute significantly to ranitidine distribution in the gastrointestinal tract.     

NSAID-induced gastrointestinal damage: the biochemical consequences of the 'ion trapping' hypothesis

There is irrefutable evidence that cyclooxygenase-1 (COX-1) inhibition by itself is not the only factor in the development of the gastrointestinal damage of NSAIDs. One suggestion is that the 'topical' effect of NSAIDs is an important initiating factor in their toxicity ('ion trapping hypothesis'), but the biochemical mechanisms are unknown. We made an integrated approach to elucidate the biochemical basis of the 'topical' toxicity of NSAIDs.Assay of specific intestinal subcellular organelle marker enzymes following indomethacin shows that only brush border and mitochondria are affected. Electron microscopy shows mitochondrial changes characteristic of uncoupling of mitochondrial oxidative phosphorylation (or inhibition of the respiratory chain) following NSAIDs. In vitro studies show that the mitochondrial effects relate to the acidity (pKa) of the NSAID, which is also crucial for their binding (inhibition) to the COX enzymes.We attempted to dissociate the two effects. Enantioners (R and S) of flurbiprofen have a differential effect on COX inhibition. We show that both enantiomers are associated with changes in mitochondrial morphology, increase in intestinal permeability and inflammation, but only the S-enantiomer (which decreases intestinal mucosal prostaglandin levels) is associated with intestinal ulceration. In a separate set of experiments we show that the uncoupler, dinitrophenol, altered intestinal mitochondria, increased intestinal permeability and inflammation, but caused no ulcers. Parenteral aspirin, which does not have a 'topical' effect, decreased intestinal mucosal prostaglandin levels significantly but was not associated with any other pathophysiogical alterations. Given together, the two drugs were associated with the same damage as indomethacin. These studies show a clear dissociation of the 'topical' and COX inhibitory effects of NSAIDs. We suggest that the 'topical' effect of NSAIDs is instrumental in initiating the intestinal damage of conventional NSAIDs and that inhibition of COX modifies this response leading to severe inflammation and ulcers.     

药物的肠吸收与处置研究进展

对近几年药物肠吸收与处置方面的研究进展进行了综述。包括:特定部位吸收、代谢的认识和利用,与药物首过效应有关的肠壁外泌及代谢作用的介绍,促进药物肠道吸收的方法及常用研究模型的比较。     

Determining small bowel integrity following drug treatment

Intestinal integrity is maintained by a delicate balance between mucosal defence and luminal aggressors that cause damage if exposed to the mucosa. The intestinal barrier function appears to be the gatekeeper for controlling this balance. It is becoming increasingly clear that if the intestinal barrier is disrupted the consequences are low grade intestinal inflammation which carry with it the risk of significant blood and protein loss both of which may cause clinical management problems. We review the strength and weaknesses of methods for assessing small bowel function that are useful for assessing drug-induced intestinal toxicity. There are a number of imaging methods for assessing intestinal integrity but these do not provide functional information. Intestinal permeability measurements have been optimized for specificity and there are now ways of measuring intestinal permeability regionally, but marker analyses continue to be cumbersome. Recent developments of faecal inflammatory markers make it a matter of routine to assess this in any routine chemical pathology laboratory. Bleeding, protein loss and other complications of inflammation can also be measured with good specificity, but again the methods are cumbersome. Using a combination of functional and imaging techniques it is now possible to characterize and define with precision, the small bowel side-effects of drugs, the best example being the small bowel side-effects of nonsteroidal anti-inflammatory drugs (NSAIDs).     

Intestinal propulsive action of oxetoron

Summary In a double blind placebo controlled study of 40 patients, oxetoron was shown significantly to shorten the time required for movement of a small intestinal biopsy capsule up to the angle of Treitz.Oxetoron (nocertone^®) Labaz     

大肠粘液腺癌107例临床分析

目的：探讨大肠粘液腺癌的临床病理特性及其综合治疗方面应该注意的问题。方法：回顾性分析107例大肠粘液腺癌临床和病理资料。结果：（1）与非粘液腺癌相比，大肠粘液腺癌好发于青年人（年龄＜45岁）；（2）粘液与非粘液腺癌皆好发于直肠，但粘液腺癌更多发于升结肠；（3）易向周围脏器组织浸润生长；（4）易发性远处淋巴结转移；（5）根治性手术切除率低；（6）术后复发率高，预后较差。结论：大肠粘液腺癌是一类预后较差的大肠癌，对大肠癌粘液癌应该采用较积极的综合治疗方式。     

Blood flow in intestinal absorption models

Up to the present, ten models have been proposed or applied to analyze the relationship between blood flow and intestinal absorption. The conceptions of these models and their basic and final equations are described. In addition, their relationship to the first-order rate constants used in the models not explicitly including the blood flow rate is elucidated. Usually a curvilinear (concave curvature) relationship between the blood flow rate and the absorption rate is predicted by the models. This similarity of the curves is the reason that in many cases several models are compatible with the experimental data.     

海兔素对乳腺肿瘤大鼠肠道屏障损伤的保护作用△

目的 探讨海兔素对二甲基苯蒽(7,12-dimethylbenz(a)anthracene, DMBA)诱发的乳腺肿瘤大鼠肠道屏障损伤的保护作用。方法30只雌性SD大鼠按体质量随机分为正常对照组(C)、模型组(M)和海兔素干预组(A)。模型组及海兔素干预组大鼠右侧臀部皮下一次性注射100 mg/kg DMBA建立乳腺癌模型。观察各组大鼠乳腺癌发生率及抑瘤率;酶联免疫吸附实验(ELISA)检测血浆中IL-4、IL-10、IL-6、TNF-α 浓度及D-乳酸(D-LA)和二胺氧化酶(DAO)的水平;实时荧光定量PCR技术(Real-Time PCR)对大鼠粪便肠道菌群16s RDNA V3可变区进行定量分析。结果 与模型组比较,海兔素组大鼠肿瘤潜伏期延长,肿瘤发生率和平均瘤质量降低(P均<0.05),抑瘤率达到49.83%,且该组胸腺指数明显升高(P<0.05);ELISA结果显示,与模型组比较,海兔素干预组IL-4浓度显著升高(P<0.05),IL-6的浓度显著降低 (P<0.05),D-LA的浓度显著降低(P<0.05);RT-PCR结果显示,海兔素干预后,大肠杆菌显著性降低(P<0.05),柔嫩梭菌及乳酸杆菌显著性升高 (P<0.05)。 结论 海兔素对大鼠乳腺肿瘤生长具有一定抑制作用,其作用机制可能与修复乳腺癌大鼠肠道屏障相关。     

miRNA在肠缺血再灌注损伤中作用及机制的研究进展

microRNA(miRNA)是一类广泛存在于动植物的由19~25个核苷酸组成的具有高度保守性的单链非编码RNA,其生物学效应是通过与mRNA互补配对在转录后水平负调控靶基因的表达。肠缺血再灌注(I/R)损伤在临床实践中较为常见,缺血再灌注后会导致肠黏膜屏障损伤,且与临床上众多疾病的发生、发展与转归都有一定的联系。目前有众多研究显示,miRNA的亚型基因miR-34a-5p、miR-351-5p、miR-682、miR-21等在一定程度上通过调控一系列信号转导进而影响肠I/R损伤的发生、发展。因此,揭示miRNA在肠I/R损伤中作用机制,并可为肠I/R损伤的临床诊断及治疗提供新的方向。