鸡冠花黄酮对糖尿病大鼠骨形态形成性蛋白2、尿无机盐及微量溶菌酶含量的影响

目的:探讨鸡冠花黄酮化合物对糖尿病大鼠骨形态形成性蛋白2(BMP2)、尿无机盐以及微量溶菌酶含量的影响。方法:雌性SD大鼠24只,随机分为正常对照组(CN)、糖尿病模型组(DM)和椅尿病加鸡冠花黄酮组(CRIST,100 mg·kg-1·d-1),实验10周,测骨密度和24 h内尿液钙、钠、钾的排出量及微量溶菌酶含量,用免疫组化法测骨骼中BMP2的表达。结果:DM组与CN组比,大鼠尿钙、钠排出量显著增高,而尿钾排出量及骨BMP2表达降低(P<0．05);溶菌酶含量显著增高,肾小管的重吸收功能降低。CRIST组与DM组比较,大鼠尿钙、钠排出量显著降低,骨BMP2显著性升高,溶菌酶含量显著降低。结论:鸡冠花黄酮类化合物可调节糖尿病大鼠无机盐代谢及骨BMP2表达,提高肾小管的重吸收功能,预防糖尿病大鼠骨质疏松的发生。     

尼古丁对兰索拉唑及其代谢产物在大鼠体内药动学的影响

目的:研究尼古丁对兰索拉唑及其代谢产物5-羟基兰索拉唑和兰索拉唑砜在大鼠体内药动学特征的影响。方法:16只大鼠随机分为2组,单独用药组皮下注射生理盐水后口服兰索拉唑8 mg.kg-1;联合用药组皮下注射尼古丁1 mg.kg-1后口服兰索拉唑8 mg.kg-1。于给药后不同时间点采集血样,用LC-MS/MS法测定血药浓度,通过对兰索拉唑及细胞色素P450酶(CYP)2C19代谢产物5-羟基兰索拉唑和CYP3A4代谢产物兰索拉唑砜血药浓度的测定,计算大鼠体内药动学参数,以5-羟基兰索拉唑、兰索拉唑砜与兰索拉唑AUC0-4h的比值分别作为CYP2C19、CYP3A4酶活性的指标,研究尼古丁对大鼠体内兰索拉唑代谢的影响。结果:尼古丁显著降低了兰索拉唑的AUC(0-4h),从(487.1±165.5)ng.h-1.L-1降至(270.0±73.4)ng.h-1.L-1(P<0.05);显著提高了5-羟基兰索拉唑与兰索拉唑的AUC(0-4h)的比值,从(0.27±0.06)增至(1.0±0.5)(P<0.01);显著降低了兰索拉唑砜与兰索拉唑的AUC(0-4h)的比值,从(1.9±0.7)降至(0.37±0.14)(P<0.01)。结论:尼古丁降低了兰索拉唑体内的生物利用度,其原因可能与尼古丁对CYP2C19酶的诱导作用有关。     

实验性糖尿病大鼠阴茎海绵体组织自由基代谢的研究

目的：通过体内实验，探讨试验性糖尿病大鼠阴茎海绵体组织自由基变化。方法：采用黄嘌呤氧化法测定超氧化物岐化酶（SOD）活性，用改良巴比妥酸微量法测定丙二醛（MDA）含量。结果：糖尿病大鼠阴茎海绵体组织SOD明显低于对照组（P＜0．01），MDA明显升高（P＜0．001）。结论：在本实验条件下，实验性糖尿病大鼠阴茎海绵体组织自由基代谢明显障碍，这种变化可能在糖尿病患者阳痿的发生发展中起一定作用。     

缩泉胶囊对自然衰老大鼠尿量及尿中离子浓度的影响

目的观察缩泉胶囊对自然衰老大鼠24h尿量、水负荷后5h尿量及尿中Na+、K+、Cl-浓度的影响。方法取老年大鼠(20月龄)50只,青年大鼠(3月龄)10只。设置组别为:空白对照组、模型对照组、金匮肾气丸组、缩泉胶囊高、中、低剂量组。用代谢笼法测量大鼠24h尿量及水负荷5h尿量;用生化分析仪测定尿液中Na+、K+、Cl-浓度。结果缩泉胶囊中、高剂量组24h尿量明显减少;缩泉胶囊低、中、高剂量组水负荷后5h内尿量明显减少;缩泉胶囊低、中、高剂量组尿液中Na+、Cl-排出量明显减少(P<0.05~0.01);缩泉胶囊中、高剂量可以显著增加自然衰老大鼠尿液中K+的排出量(P<0.05)。结论自然衰老大鼠多尿的发生可能与Na+、K+及Cl-排泄异常有关,而缩泉胶囊可使"肾虚多尿"大鼠尿Na+、Cl-排出减少,尿K+排出增加,同时尿量明显减少,表明其抗利尿作用可能是通过保钠排钾的作用实现的。     

青蒿琥酯毒性作用机理初探

<正> 用电子自旋共振法(ESR)测定青蒿琥酯在体内、外代谢转化过程中是否产生自由基,用硫代巴比妥酸(TBA)法测定Wistar大鼠iv该药后肠、肝组织内丙二醛含量,以光学和电子显微镜观察抗氧化剂维生素E是否能对抗该药对肠、肝造成的病理损伤。结果表明,该药在体内、外代谢过程中均产生自由基;肠、肝组织中丙二醛的含量药后明显增高,且持续达6 d之久,增高程度与给药剂量呈正相关,药后24 h的相关系数(r)肠、肝     

肾复康胶囊的抗炎作用与NO的关系研究

目的：为探讨肾复康胶囊治疗肾炎的机理，研究肾复康的抗炎作用与NO的关系，方法：应用镉还原柱层析和Griess反应法测定NO的稳定代谢产物NO2^-(NO3^-)。结果：肾复康对正常大鼠血，尿中亚硝酸盐（硝酸盐）[NO2^-(NO3^-)]含量无显著影响；能不同程度地抑制角叉菜胶所 大鼠中足跖肿胀，并显著地降低血清，尿液和炎性足跖组织中NO2^-(NO3^-）含量；使棉球肉芽肿大鼠模型中棉球肉芽肿重量减轻，显著降低血清，尿液和炎症组织中NO2^-(NO3^-)的含量。结论：肾复康对正常大鼠体内NO的产生没有影响；其抗炎（大鼠角叉菜胶性足跖肿胀和棉球肉芽肿）作用与抑制其体内NO水平有关。肾复康抑制体内NO水平可能是与其治疗肾炎有效的可能机制。     

A771726在大鼠尿中代谢产物

目的：研究静脉给药途径A771726在大鼠尿液中的代谢产物。方法：大鼠静脉给药A771726（30mg／kg）,分别采集给药前及给药后0-48h尿液,合并后冷存。用电喷雾离子阱多级质谱法（LC／MS）对A771726及其在大鼠尿中的代谢产物进行分析。结果：大鼠静脉给药A771726后,经过与空白尿液对比,在尿液中发现3种代谢产物,推测其结构分别是甲基化羟甲基化,亚甲基醇半缩甲醛化A771726。结论：A771726在大鼠尿中代谢产物以Ⅰ相代谢为主,未发现Ⅱ相代谢产物。与文献报道通过灌胃途径给药所测到的代谢产物结构相同,其代谢物的结构及含量有待于进一步分析后确证。     

尼古丁依赖大鼠脑组织中β－内啡肽含量的变化

本研究的目的在于探讨尼古丁对脑组织（皮层、海马、纹状体和丘脑等四个脑区）中β－内啡肽含量的影响，采用放射免疫方法定量测定，观察大鼠形成尼古丁身体依赖性过程中脑组织β－内啡肽含量的动态变化。结果显示：尼古丁急性给药（２．５Ｃｇ·ｋｇ－１，ｓｃ）可使四个脑区中β－内啡肽的含量明显升高。且能被美加明特异阻断；在尼古丁连续递增给药形成身体依赖的过程中，大鼠脑组织中β－内啡肽的含量也持续维持在高浓度水平。这些结果表明，尼古丁是通过兴奋中枢烟碱样胆碱能受体继而使亮啡肽含量升高；大鼠形成尼古丁依赖可能与脑内源性阿片肽含量的升高密切相关。     

口服加替沙星在大鼠体内的排泄

目的:观察大鼠单剂量口服加替沙星后的体内排泄情况.方法:选取20只Wistar大鼠,随机分为尿液、粪便和胆汁排泄组,分别单剂量(63 mg/kg)灌服加替沙星后,收集72 h内尿液、粪便和胆汁排泄量.采用HPLC法测定尿液、粪便和胆汁中加替沙星浓度.结果:大鼠单剂量灌服加替沙星后尿液中排出量为17%,粪便中排泄量为11.2%,胆汁中排泄量为2%.结论:加替沙星口服后主要由尿液、粪便排泄.     

五种螯合剂对大鼠体内微量元素影响的观察

观察了５种常用螯合剂对大鼠体内微量元素排出量、组织分布的变化。结果表明，５种螯合剂可不同程度地增加机体必需微量元素Ｚｎ、Ｃｕ、Ｍｇ和Ｃａ经尿液排出量。ＥＤＴＡ和ＤＴＰＡ的影响尤为明显。ＥＤＴＡ和ＤＴＰＡ可使Ｚｎ经尿液的排出量增加１６－５２倍，ＤＴＰＡ使肝脏Ｚｎ含量减少１５．９％（Ｐ〈０．０５），肝脏Ｃｕ含量下降６０％（Ｐ〈０．０５）。ＥＤＴＡ和ＤＴＰＡ注射后，肾中Ｚｎ含量明显增高，相当对照大鼠３．     

Pharmacokinetics of nicotine in rats after multiple-cigarette smoke exposure

The pharmacokinetics of nicotine and its major metabolites was evaluated in male rats after multiple-cigarette smoke exposure. A smoke-exposure apparatus was used to deliver cigarette smoke to the exposure chamber. The rats were exposed to smoke from a single cigarette every 8 hr for 14 days and to the smoke of a cigarette spiked with radiolabeled nicotine on the 15th day. Blood and urine samples were collected at timed intervals during the 10-min smoke-exposure period of the last cigarette and up to 48 hr thereafter. Nicotine, cotinine, and other polar metabolites were separated by thin-layer chromatography and quantified by liquid scintillation counting. The data were analyzed by computer fitting, and the derived pharmacokinetic parameters were compared to those observed after a single iv injection of nicotine and after a single-cigarette smoke exposure. The results indicated that the amount of nicotine absorbed from multiple-cigarette smoke was approximately 10-fold greater than that absorbed from a single cigarette. Also, unlike the single-cigarette smoke exposure experiment, nicotine plasma levels did not decay monotonically but increased after the 5th hr, and high plasma concentrations persisted for 30 hr. The rate and extent of the formation of cotinine, the major metabolite of nicotine, were decreased as compared with their values following a single-cigarette smoke exposure. It was concluded that nicotine or a constituent of tobacco smoke inhibits the formation of cotinine and may affect the biotransformation of other metabolites. Urinary excretion tended to support the conclusions that the pharmacokinetic parameters of nicotine and its metabolites were altered upon multiple as compared to single dose exposure.     

Effects of cigarette nicotine content on smoking behavior of baboons

Human cigarette smokers modify the way in which they smoke cigarettes of differing nicotine content, apparently to maintain nicotine exposure at a preferred level. The effects of changing from moderate to high or low nicotine content cigarettes were examined in 11 baboons (superspecies Papio cynocephalus) trained to smoke cigarettes for water rewards. Relative to the moderate nicotine content cigarette, the animals took significantly (p < .05) more puffs on the high nicotine content cigarette, and the puffs on the high nicotine cigarette were significantly larger in volume. The animals made the same number of puffs, relative to the moderate nicotine content cigarette, on the low nicotine content cigarette, but the volume of the puffs was significantly smaller. The cotinine output in urine varied significantly and was directly related to cigarette nicotine content; cotinine is the primary metabolite of nicotine. Baboons, like people, prefer high nicotine content cigarettes. Nonhuman primates also regulate nicotine exposure by modification of their puffing behavior. These results indicate that the nonhuman primate also can be used as a model for the investigation of the behavioral aspects of cigarette smoking.     

Relationship between the level and time of exposure to tobacco smoke and urine nicotine and cotinine concentration

The study attempts to evaluate whether it is possible to determine time and level of exposure of rats to tobacco smoke based on nicotine and cotinine content in urine. The animals were exposed to tobacco smoke by inhalation in a specially designed experimental chambers. The exposure to three different tobacco smoke levels (500, 1000 and 1500 mg CO/m3 of air) lasted 6 h per day, for one, three and five days. Nicotine and cotinine concentrations were measured in daily urine using high performance liquid chromatography procedure developed by the authors. It has been shown that cotinine but not nicotine can be used as a biomarker of time and extent of exposure to tobacco smoke.     

Plasma nicotine and cotinine in tobacco smoke exposed beagle dogs

Nicotine and cotinine have been determined in plasma samples from 87 beagle dogs chronically exposed to cigarette smoke with three different levels of nicotine. An additional 18 sham-exposed animals were included in the study as controls. Smoke was administered to the animals through permanent tracheostomas via cuffed tracheostomy tubes and was generated from reference cigarettes under standard puffing parameters by ADL-II smoking machines. The dogs were exposed for an average of 2 years prior to sample collection. The results from blood samples collected at specific intervals in the daily exposure schedules indicate that nicotine may be useful as a relative index of smoke exposure. At elevated exposure levels, average blood concentrations were related to the number of cigarettes smoked as well as the nitocine delivery of the cigarette. Cotinine was found to increase more slowly than nicotine and was also metabolized more rapidly than in humans. Overall, the study affords an examination of the relationship of plasma nicotine and cotinine with estimated nicotine exposure.     

High performance liquid chromatographic determination of nicotine and cotinine in plasma and nicotine and cotinine, simultaneously, in urine

Three analytical procedures were developed to determine nicotine in plasma, cotinine in plasma and, simultaneously, nicotine and cotinine in urine. After liquid or solid-phase extraction, the purified aqueous phase is injected into a high performance liquid chromatograph equipped with an ultra-violet detector using a CN Spheri-5 micron cartridge-column with an inner diameter of 4.6 mm and a length of 10 or 22 cm. The limit of quantitation for nicotine in plasma was around 8 to 15 ng/ml, that of cotinine in plasma around 50 ng/ml and that of nicotine and cotinine in urine around 170 ng/ml and 70 ng/ml, respectively. The limit of detection of nicotine in plasma was around 1 ng/ml and that of nicotine and cotinine in urine around 20 ng/ml and 10 ng/ml, respectively. The passive exposure to cigarette smoke by non-smokers and the "resting levels" of nicotine in plasma and urine of smokers were studied. The analytical methods were set up to study the pharmacokinetics and bioavailability of nicotine in healthy volunteers following single and repeated administrations of different doses of transdermal nicotine systems.     

Pharmacokinetic study of nicotine and its metabolite cotinine to clarify possible association between smoking and voiding dysfunction in rats using UPLC/ESI-MS

The present study was undertaken to clarify the possible association between nicotine intake/cigarette smoking and detrusor instability. For pharmacokinetic characterization of nicotine and cotinine (a major and pharmacologically less active metabolite of nicotine), a rapid ultra-performance liquid chromatography/electrospray ionization-mass spectrometry (UPLC/ESI-MS) method was developed that requires only a small amount of sample and simple pretreatment. The UPLC/ESI-MS method was validated with a focus on specificity, sensitivity (limit of detection, 2.5 ng/mL; limit of quantification, 5 ng/mL), linearity (r > 0.998), accuracy (97.2-102.8%), precision (relative standard deviation <8%) and robustness in accordance with ICH guidelines (Q2B Validation of Analytical Procedures: Methodology). The developed method was successfully applied to determine nicotine and cotinine levels in rat biological samples such as plasma, urine and several tissues. After subcutaneous administration of nicotine ditartrate (2 mg/kg of body weight) in rats, the absorbed nicotine was rapidly and extensively metabolized into cotinine. However, nicotine was found to be predominant in cortex and bladder, where nicotinic acetylcholine receptors were expressed for neuronal control of voiding function. Repeated administration of nicotine led to a ca. 3-fold higher accumulation of nicotine than that of cotinine in rat urine. The results of the pharmacokinetic study using the UPLC/ESI-MS method further support the possible involvement of nicotine in increased risk of urinary dysfunction in smokers.     

Pharmacokinetics and bioavailability of nicotine in healthy volunteers following single and repeated administration of different doses of transdermal nicotine systems

Healthy nicotine-dependent smokers were applied different doses of transdermal nicotine systems (TNS) during single and repeated administrations. Plasma and urine nicotine and cotinine concentrations were determined by high performance liquid chromatography (HPLC). After single application of TNS, the maximal concentration (Cmax) and area under curve (AUC) of nicotine in plasma as well as the amount of nicotine excreted in urine were linearly related to the dose. The stable urinary cotinine excretion was not influenced by the amount of nicotine delivered by the TNS. The relevant 24 h plasma nicotine concentration reached after TNS application compares well with the plasma nicotine footpoints--not the peaks--observed in moderate to heavy cigarette smokers. A comparison between different nicotine doses from different TNS allowed to conclude to the functionality of the systems as regards pharmacokinetics and bioavailability. One or two hours after removal of the systems, there was a very slow decline of the nicotine concentrations. After repeated application of TNS, there was evidence for only a very limited nicotine accumulation in plasma (+14%) or in urine (+9%) over 10 days. The steady-state of nicotine was reached within 4 days. The continuous delivery of nicotine over 24 h resulted in an early morning plasma concentration which probably decreases or prevents the craving for the first cigarette.     

Plasma nicotine and cotinine levels following intravenous nicotine self-administration in rats

  Rationale: The route of nicotine administration between animal models and humans is very different and further investigation by determining levels of nicotine entering into the circulatory system is warranted. Objective: The present study addresses the validity of the rat self-administration procedure by comparing plasma levels of nicotine in the rat with levels reported in smokers following cigarette consumption. Methods: Plasma levels of nicotine and its metabolite cotinine were measured in 17 rats following intravenous self-administration of a range of nicotine doses (0.015, 0.03 and 0.06 mg/kg per infusion). Results: The two larger unit doses supported reliable self-administration behaviour with no overall difference in the patterns of nicotine intake. However, the total nicotine intake over the 2-h session was related to unit dose and this correlated highly with nicotine and cotinine levels measured in blood collected from the tail vein. On average, cotinine levels (50–200 ng/ml) were approximately 2-fold higher than nicotine levels (40–120 ng/ml) in plasma. Following an extinction test for one session in which saline was substituted for nicotine, no change in behaviour was observed in the two groups, while plasma levels of nicotine and cotinine dropped to nominal levels. Conclusions: The concentrations of nicotine attained following nicotine self-administration appear to be similar to levels reported in smokers after cigarette consumption, providing further validation of this procedure as an animal model of nicotine dependence. Received: 14 November 1998 / Final version: 4 January 1999     

The analysis of nicotine-1‘-N-oxide in urine,in the presence of nicotine and cotinine,and its application to the study of in vivo nicotine metabolism in man

A rapid quantitative assay for nicotine-1′-N-oxide in urine, in the presence of nicotine and cotinine, is reported. The urinary excretion of nicotine, cotinine and nicotine-1′-N-oxide was determined after nicotine had been administered in cigarette smoke, orally, or intravenously to subjects with either fluctuating, controlled acidic or controlled alkaline urinary pH. The urinary excretion of the N-oxide in 24 h from smokers under normal conditions was about half that of the cotinine excretion; more trans- than cis-diastereoisomer of nicotine-1′-N-oxide was excreted.     

Vaccination against nicotine alters the distribution of nicotine delivered via cigarette smoke inhalation to rats

Preclinical models of nicotine vaccine pharmacology have relied on i.v. or s.c. administration of nicotine. Models using cigarette smoke inhalation might more accurately simulate nicotine exposure in smokers. Nicotine vaccine effects were examined in rats using two cigarette smoke exposure models: a 10 min nose-only exposure (NSE) producing serum nicotine levels equivalent to the nicotine boost from 1 cigarette in a smoker, and a 2 h whole-body exposure (WBE) producing serum nicotine levels similar to those associated with regular mid-day smoking. Vaccination prior to 10 min smoke NSE reduced nicotine distribution to brain by 90%, comparable to its effect on nicotine administered i.v. Vaccination prior to 2 h smoke WBE reduced nicotine distribution to brain by 35%. The nicotine concentration in broncheoalveolar lavage (BAL) fluid obtained after 2 h WBE was increased by 230% in vaccinated rats but was also increased in rats passively immunized with a nicotine-specific monoclonal antibody, and so was likely due to transfer of antibody from serum rather than local production at the pulmonary mucosa. Nicotine-specific IgA was not detectable in BAL fluid, but titers in serum were appreciable at 21–25% of the IgG titer and could contribute to vaccine efficacy. Both vaccination and passive immunization are effective in reducing nicotine distribution to brain in rats when nicotine is delivered via inhaled cigarette smoke. These data validate results previously obtained in rodents for nicotine vaccines using i.v. or s.c. nicotine dosing and provide a quantitative method for studying aspects of nicotine exposure which are unique to cigarette smoke inhalation.