Covalent Binding of Inhaled Formaldehyde to DNA in the Respiratory Tract of Rhesus Monkeys: Pharmacokinetics, Rat-to-Monkey Interspecies Scaling, and Extrapolation to Man

Covalent Bindingoflnhaled Formaldehyde to DNA in the RespiratoryTractofRhesus Monkeys: Pharmacokinetics, Rat-to-Monkey InterspeciesScaling, and Extrapolation to Man. CASANOVA, M., MORGAN, K.T., STEINHAGEN, W. H., EVERITT, J. I., POPP, J. A., AND HECK,H. D'A. (1991). Fundam. Appl Toxicol 17, 409–428. DNA-proteincross-links were formed in the respiratory tract of rhesus monkeysexposed to [¹⁴C]formaldehyde (0.7, 2, or 6 ppm; 6 hr). Concentrationsof cross-links (pmol/mg DNA) were highest in the mucosa of themiddle turbmates; lower concentrations were produced in theanterior lateral wall/septum and nasopharynx. Very low concentrationswere found in the larynx/trachea/carina and in the proximalportions of the major bronchi of some monkeys exposed to 6 ppmbut not to 0.7 ppm. No cross-links were detected in the maxillarysinuses or lung parenchyma. The pharrnacokinetics of cross-linkformation in the nose were interpreted using a model in whichthe rate of formation is proportional to the tissue concentrationof formaldehyde. The model includes both saturable and nonsaturableelimination pathways and describes regional differences in DNAbinding as having an anatomical rather than a biochemical basis.Using this model, the concentration of cross-links formed incorrespondmg tissues of different spacies can be predicted byscaling the pharmacokinetic parameter that depends on minutevolume () and quantity of nasal mucosal DNA (M_DNA). The concentration-response curve for the average rateof cross-link formation in the turbinates lateral wall, andseptum of rhesus monkeys was predicted from that of F-344 ratsexposed under similar conditions. There was significant overlapbetween predicted and fitted curves, implying that V and M_DNAare major determinants of the rate of cross-link formation inthe nasal mucosa of different species. Concentrations of cross-linksthat may be produced in the nasal mucosa of adult men were predictedbased on experimental data in rats and monkeys. The resultssuggest that formaldehyde would generate lower concentrationsof cross-links in the nasal mucosa of humans than of monkeys,and much lower concentrations in humans than in rats. The rateof formation of DNA-protein cross-links can be regarded as asurrogate for the delivered concentration of formaldehyde. Useof this surrogate should decrease the uncertainty of human cancerrisk estimates derived by interspecies extrapolation by providinga more realistic measure of the delivered concenmtion at criticaltarget sites.     

Age-Dependent Pharmacokinetic Changes of Ethylenediamine in Fischer 344 Rats Parallel to a Two-Year Chronic Toxicity Study

Age-Dependent Pharmacokinetic Changes of Ethylenediamine inFischer 344 Rats Parallel to a Two-Year Chronic Toxicity Study.YANG, R. S. H., TALLANT, M. J., AND MCKELVEY, J. A. (1984).Fundam. Appl. Toxicol. 4, 663–670. As part of a 2-yearchronic toxicity study, the phannacokinetics of ethylenediamine(EDA) was studied in Fischer 344 rats of both sexes at day zero(naive animals), 6 months (controls and high level animals),and 18 months (controls and high level animals). The rats, whichwere randomized along with the rest of the animals on the toxicitystudy, were taken for pharmacokinetic experiments at the specifiedtime. A single per os (po) dose of 50 mg [¹⁴C]EDA - 2HCI/kgwas given to each rat and the plasma kinetics was followed fora 24-hr period. Five pharmacokinetic parameters (absorptionrate constant, terminal half-life, area under the curve, volumeof distribution, and ^l4CO₂ production rate constant) were comparedwith respect to age, sex, and chronic dosing. There were noapparent age-, sex-, and/or chronic dosing-related differencesin absorption rate constant and terminal half-life. However,age-related changes in area under the curve (AUC) were evident.The older rats had higher values (generally two- to threefold)for AUC than the younger rats. This age-related difference inAUC is closely associated with the volumes of distribution (V_dof the animals of varying ages. On the basis of liters per kilogram,the V_d's of the older rats are approximately one-fourth to one-halfof those for the younger (zero day) rats. The ¹⁴CO₂ productionrate constant was derived from the rate of formation of ¹⁴CO₂as a result of [¹⁴C]EDA - 2HCl dosing. The comparison of thisconstant under the various experimental conditions suggestssex-related differences. The findings of this study demonstratedage-, and to a lesser extent, sex-related differences. Chronicdosing-related changes are minimal These results are discussedin light of the chronic toxicity findings.     

吸入类药物临床前研究中鼻组织脱钙技术优化：用于大鼠鼻黏膜组织病理学检查

目的 研究不同脱钙液对大鼠鼻组织的脱钙作用及其病理切片染色效果。方法 选择10%乙二胺四乙酸（ethylene diamine tetraacetic acid,EDTA）、10%甲酸、5%硝酸脱钙液3种不同脱钙液,在室温静置及微波条件下,对大鼠鼻组织的脱钙时间和脱钙效果进行比较分析,综合评估骨组织经不同脱钙方法后制成病理切片质量。结果 常温条件下鼻组织经过EDTA脱钙液所需脱钙时间最长,微波条件下鼻组织经硝酸脱钙液所需脱钙时间最短,经EDTA脱钙液的鼻组织切片质量、HE染色、MASSON染色和免疫组化染色中质量最佳,硝酸脱钙液的鼻组织的切片质量最差,甲酸脱钙液的鼻组织HE染色效果较佳,MASSON和免疫组化染色质量略差。结论 EDTA脱钙液配合微波进行的鼻组织脱钙,脱钙效率明显提升,且切片和染色效果俱佳。     

Developmental Toxicity Evaluation of Inhaled Methyl Isobutyl Ketone in Fischer 344 Rats and CD-1 Mice

Developmental Toxicity Evaluation of Inhaled Methyl IsobutylKetone in Fischer 344 Rats and CD-1 Mice. Tyl, R. W., FRANCE,K. A., FISHER, L. C., PRITTS, I. M., TYLER, T. R., PHILLIPS,R. D., and MORAN, E. J. (1987). Fundam. Appl. Toxicol. 8, 310–327.Pregnant Fischer 344 rats and CD-1 mice were exposed to methylisobutyl ketone vapor (CAS No. 108-10-1) by inhalation on GestationalDays 6 through 15 at concentrations of 0, 300, 1000, or 3000ppm (mean analytical values of 0, 305, 1012, and 2997 ppm, respectively).The animals were sacrificed on Gestational Day 21 (rats) or18 (mice), and live fetuses were examined for external, visceral,and skeletal alterations. In rats, exposure to 3000 ppm resultedin maternal toxicity expressed as clinical signs, decreasedbody weight and body weight gain, increased relative kidneyweight, and decreased food consumption, and in fetotoxicityexpressed as reduced fetal body weight per litter and reductionsin skeletal ossification. In mice, exposure to 3000 ppm resultedin maternal toxicity expressed as exposure-related increasesin deaths (12.0%, 3/25 dams), clinical signs, and increasedabsolute and relative liver weight, and in fetotoxicity expressedas increased incidence of dead fetuses, reduced fetal body weightper litter, and reductions in skeletal ossification. No treatment-relatedincreases in embryotoxicity or fetal malformations were seenin either species at any exposure concentration tested. Therewas no evidence of treatment-related maternal, embryo, or fetaltoxicity (including malformations) at 1000 or 300 ppm in eitherSpecies.     

N-Demethylation of Aminopyrine by the Nasal Mucosa in Mice and Rats

Abstract: N-demethylation of aminopyrine was demonstrated in the nasal mucosa of C57 B1 mice and Sprague-Dawley rats by measurements of the ¹⁴CO₂ formed at incubation of ¹⁴C-aminopyrine with tissue-slices. The metabolism of aminopyrine by the nasal mucosa was induced by phenobarbital pretreatment and susceptible to inhibition with metyrapone and SKF 525 A suggesting the presence of a cytochrome P-450-dependent enzyme system in the tissue. Immediately after injection of ¹⁴C-aminopyrine in rats a uniform distribution of radioactivity in the body was recorded. After thirty minutes, however, a preferential localization of radioactivity was found in the nasal mucosa and in the liver. By pretreatment with metyrapone the uptake of radioactivity in the nasal mucosa and in the liver was blocked suggesting that the observed accumulation of radioactivity is due to metabolites.     

Metabolism of Progesterone by the Nasal Mucosa in Mice and Rats

Abstract: The metabolism of 4-¹⁴C-progesterone by the nasal mucosa and lung from mice and rats was investigated in vitro. Using thin-layer radiochromatography at least 10 and 7, yet unidentified, metabolites were found at incubation with slices from the nasal mucosa and lung, respectively. The results further indicated that the rate of progesterone metabolism was higher in the nasal mucosa than in the lung. Autoradiography of lung slices incubated with ¹⁴C-progesterone showed that a selective localization of radioactivity occurred in the bronchial mucosa.     

High-Performance Liquid Chromatography Determination of Acitretin in Plasma and Its Application to a Pharmacokinetic Study in Human Subjects

Pharmaceutical Research -     

Evaluation of the Teratogenicity of Ethylenediamine Dihydrochloride in Fischer 344 Rats by Conventional and Pair-Feeding Studies

Ethylenediamine dihydrochioride (EDA·2HCl) was fed togroups of 20(40 controls) timed-pregnant rats on Gestation Days6 through 15 at 1.0, 0.25, 0.05, or 0 g/kg/day. The day of discoveryof a vaginal plug was considered gestation day 0. On GestationDay 21, the fetuses were delivered by cesarean section, andthe standard endpoints for teratogenicity were evaluated. At1.0 and 0.25 g/kg/day, reductions in maternal diet consumptionand weight gain were observed during the exposure period. At1.0 g/kg/day, fetal weight and crown–rump length weresignificantly reduced and the percentage of litters with resorptions,with skeletal variants, and with missing or shortened innominatearteries was increased. To circumvent the possible problem ofpalatability of the diet and/or the effects of reduced foodintake, a probe study was performed in which 1.0 or 0 g/kg/daywas given to pregnant rats by gavage on Gestation Days 6 through15. However, food intake was also substantially reduced withgavage dosing of the test substance. To determine whether thearterial defects were the result of reduced food intake, a pair-feedingstudy was performed in which EDA·2HCl was fed on GestationDays 6 through 15 at 1.0 g/kg/day. A pair-fed control groupreceived the same amount of diet consumed by the EDA·2HCl-treatedrats. An untreated control group was fed ad libitum. All groupscontained 20 pregnant females. Maternal weight gain, fetal weightand length, and the length of the innominate artery were allreduced in the EDA·2HCl-treated group compared to bothcontrol groups. Two fetuses each in the EDA·2HCl-treatedand pair-fed control groups had missing innominate arteriesversus none in the untreated controls. The four affected fetuseswere from four different litters. Ingestion of EDA·2HClresulted in reduced maternal weight gain, fetal size, and lengthof the innominate artery, but the missing innominate arterywas not a result of EDA·2HCl treatment. Therefore, therewas no evidence of teratogenicity in Fischer 344 rats from EDA·2HClingestion during organogenesis.     

Analysis of Native Human Plasma Proteins and Haemoglobin for the Presence of Bityrosine by High-Performance Liquid Chromatography

Abstract: Generation of reactive oxygen species in vivo results in oxidative-damage to cellular components, including proteins. Due to the relatively long half-lives of several blood proteins the cumulative formation of oxidatively damaged proteins might serve as a biomarker for reactive oxygen species formation. The most prominent sources of reactive oxygen species in vivo are site-specific metal ion-catalyzed reactions of the Fenton and Haber-Weiss types and the H₂O₂/peroxidase system. In vitro oxidation of L-tyrosine using a peroxidase or Cu⁺⁺/H₂O₂ system gives rise to the formation of a highly fluorescent substance, bityrosine. High-performance liquid chromatography (HPLC) analysis of acid hydrolyzed serum albumin after oxidation with peroxidase/ H₂O₂ or with Cu⁺⁺/H₂O₂ showed that bityrosine had been formed whereas oxidation of this protein with Fe(III)/ ascorbate did not result in the formation of bityrosine. Bityrosine could not be detected in human plasma proteins or haemoglobin with the detection limit of one pmol per mg protein.     

人血浆中环丙沙星的高效液相色谱测定及其药物动力学研究

建立了测定血浆中环丙沙星浓度的反相离子对高效液相色谱法，色谱柱采用Ｃ１８Ｓｐｈｅｒｉｓｏｒｂ柱（２５ｃｍ×４．６ｍｍ，５μｍ），流动相为甲醇（０．００８ｍｏｌ／Ｌ）磷酸盐缓冲液（０．５ｍｏｌ／Ｌ）四丁基溴化铵（３０∶７５∶４，ｖ／ｖ／ｖ，ｐＨ２．６）。检测波长为２７６ｎｍ。方法检测限为４０ｎｇ／ｍｌ（Ｓ／Ｎ≥２）。该法简单，用乙腈沉淀蛋白后直接进样。应用该法研究了８名志愿者单剂量随机交叉服用环丙沙星片剂及干糖浆两种剂型后的药物动力学，结果显示，两种剂型的药物动力学参数无显著性差异，干糖浆的相对生物利用度为片剂的８４％。     

Changes in the Nasal Epithelium of Rats Exposed by Inhalation to Mixtures of Formaldehyde, Acetaldehyde, and Acrolein

Formaldehyde, acetaldehyde, and acrolein are well-known upperrespiratory tract irritants and occur simultaneously as pollutantsin many indoor and outdoor environments. The upper respiratorytract, and especially the nose, is the prime target for inhaledaldehydes. To study possible additive or interactive effectson the nasal epithelium we carried out 1- and 3-day inhalationstudies (6 hr/day) with formaldehyde (1.0, 3.2, and 6.4 ppm),acetaldehyde (750 and 1500 ppm), acrolein (0.25, 0.67, and 1.40ppm), or mixtures of these aldehydes, using male Wistar ratsand exposure concentrations varying from clearly nontoxic totoxic. The (mixtures of) aldehydes were studied for histopathologicaland biochemical changes in the respiratory and olfactory epitheliumof the nose. In addition, cell proliferation was determinedby incorporation of bromodeoxyuridine and proliferating cellnuclear antigen expression. Effects were primarily observedafter 3 days of exposure. Histopathological changes and cellproliferation of the nasal epithelium induced by mixtures ofthe three aldehydes appeared to be more severe and more extensivein both the respiratory and the olfactory part of the nose thanthose observed after exposure to the individual aldehydes atcomparable exposure levels. As far as nasal histopathologicalchanges and cell proliferation are concerned neither dose additionnor potentiating interactions occurred at no-toxic-effect levels,except for a possible potentiating effect of acetaldehyde atnoneffect levels. The results did not indicate a major rolefor aldehyde dehydrogenases in the biotransformation of thealdehydes studied. Activities of glutathione S-transferase andglutathione reductase after 3 days of exposure to acrolein,alone or in combination with formaldehyde and acetaldehyde,were depressed whereas the glutathione peroxidase activity waselevated. No decrease of nonprotein sulphydryl levels were observed.These findings suggest that, for no-toxic-effect levels, combinedexposure to these aldehydes with the same target organ (nose)and exerting the same type of adverse effect (nasal cytotoxicity),but partly with different target sites (different regions ofthe nasal mucosa), is not associated with a greater hazard thanthat associated with exposure to the individual chemicals.     

Analysis of Diltiazem and Desacetyldiltiazem in Plasma Using Modified High-Performance Liquid Chromatography: Improved Sensitivity and Reproducibility

Pharmaceutical Research -     

钙拮抗剂尼卡地平的HPLC法分析及其在兔体内药代动力学研究

目的 :建立兔血浆中钙拮抗剂尼卡地平的反相高效液相色谱分析方法 ,并对其在兔体内的药代动力学进行研究。方法 :血浆样品在弱碱性条件下经环己烷 -异丙醇 (96∶4)提取 ,用LiChrosorbC18反相柱 ,甲醇 -水(75∶2 5 )为流动相 ,流速 1 0mL·min-1,检测波长 2 36nm等条件下 ,分析测定。结果 :方法平均回收率为98 2 7%～ 10 0 4% ,RSD <5 0 % ,线性范围 :11～ 110ng (r =0 9981) ,最低检测限为 10ng。 结论 :本法操作简便、准确灵敏、重现性好 ,可用于尼卡地平的药动学研究。     

Sequential Study of the Chronic Nephrotoxicity Induced by Dietary Administration of Ethoxyquin in Fischer 344 Rats

Groups of 3-week-old male and female Fischer 344 rats were administered0.5% ethoxyquin-containing diet for varying periods of time,ranging from 4 weeks up to 18 months, to assess renal histopathology.The primary lesion observed was renal papillary necrosis inthe male rat, commencing as interstitial degeneration of thepapillary tip by 4 weeks exposure, and reaching a complete formof papillary necrosis by 24 weeks. The papillary necrosis inmale rats was consistently accompanied by active pyelonephritisaffecting the cortex, and urothelial hyperplasia in the renalpelvis. A marked sex difference was evident in that female ratsdeveloped papillary change at a later stage than males and thelesion never progressed beyond interstitial degeneration. Afurther sex difference associated with ethoxyquin treatmentwas the increasing cellular accumulation of lipofuscinrelatedpigment involving proximal tubules in female rats. Spontaneouschronic progressive nephropathy (CPN) was exacerbated by ethoxyquinin both males and females, but more so in the former. Proximaltubule hyperplasia was most frequently observed in ethoxyquin-treatedmales at the later sampling times. In all cases, such proliferativelesions were associated either with pyelonephritis or with themost advanced stages of CPN. Contrary to a previous report,there was no evidence that ethoxyquin directly induced preneoplasticrenal tubule hyperplasia.     

Dose Dependence of Covalent Binding of Acrylonitrile to Tissue Protein and Globin in Rats

The dose dependence of acrylonitrile (AN) covalent binding totissue protein, following a single acute exposure over a 100-foldrange in dose, was measured. Covalent binding was a linear functionof AN dose in the lower dose range (0.0–0.95 mmol AN/kg).The slopes of the dose-response curves indicated that tissuesvaried by nearly 10-fold in their reactivity with AN. The relativeorder of covalent binding was as follows: blood > kidney= liver > forestomach = brain > glandular stomach >muscle. Similar dose-response behavior was observed for globintotal covalent binding and for globin N-(2-cyanoethyl)vallne(CEValine) adduct formation. The latter adduct was found torepresent only 0.2% of the total AN adduction to globin. Regressionof tissue protein binding versus globin total covalent bindingor globin CEValine adduct indicated that both globin biomarkerscould be used as surrogates to estimate the amount of AN boundto tissue protein. At higher AN doses, above approximately 1mmol/kg, a sharp break in the covalent binding dose-responsecurve was observed. This knot value is explained by the nearlycomplete depletion of liver glutathione and the resultant terminationof AN detoxification. The toxicity of AN is known to increasesharply above this dose. The data suggest that a comparisonof specific tissue proteins labeled by AN above and below thisthreshold dose may provide some insight into the mechanism ofAN-induced toxicity.     

Measurement of Nuclear DNA Modification by 32P-Postlabeling in the Kidneys of Male and Female Fischer 344 Rats after Multiple Gavage Doses of Hydroquinone

Oral administration of hydroquinone (HQ) to male Fischer 344(F344) rats results in dose-related kidney toxicity beginningwith mild enzymuria by 1 week, significant cell proliferationby 6 weeks, and nephropathy and an increase in the incidenceof renal tubule adenomas after 2 years. Female F344 rats, B6C3F1mice, Sprague-Dawley rats, dogs, and humans are resistant tothe renal toxicity of HQ associated with repeated exposure.To determine the potential of HQ to induce covalent DNA adductsin the kidney, male and female F344 rats were given 0, 2.5,25, or 50 mg/kg HQ by gavage for 6 weeks, and nuclear DNA isolatedfrom kidneys was analyzed by the ³²P-postlabeling assay. At50 mg/kg, males, but not females, showed an increase in therate of excretion of N-acetyl-ß-D-glucosaminidase,indicative of proximal tubular damage. Analysis of nuclear DNApreparations by the postlabeling assay showed that HQ does notproduce covalent DNA adducts in the kidneys of male and femalerats. The assay's lower limit of detection is 1 adduct in 10⁹to 10¹⁰ DNA nucleotides. No treatment-related increases in backgroundradioactivity levels on the chromatograms were seen at locationscorresponding to the major in vitro adducts of HQ and p-benzoquinone.HQ treatment, however, resulted in the reduction of the levelsof certain endogenous adducts (I-compounds), the biologicalsignificance of which is unknown. The results indicate thatHQ does not produce covalent DNA adducts in the kidneys of maleand female rats after repeated oral administration at nephrotoxicdose levels, and suggest a nongenotoxic etiology of benign tumorsin the kidneys of male F344 rats treated with HQ.     

滋肾丸中肉桂酸在大鼠体内的测定及药动学研究

目的建立简便的测定大鼠血浆中肉桂酸血药浓度的高效液相色谱法.方法样品血浆以1 moL·L-1HCI酸化,用乙酸乙酯萃取,取上清液进行分析.色谱条件为:流动相:甲醇-乙腈-水-三乙胺(7:22:73:0.2,V/V),磷酸调pH=4,流速:0.9 mL·min-1,检测波长:340nm.结果肉桂酸的血药浓度标准曲线的线性范围为1.92-192.0μg@mL-1,其最低定量限为1.92μg·mL-1,日内及日间RSD均小于8%.平均回收率为82.0%.大鼠口服滋肾丸后在体内的药动学参数为:Tmax≈0.5 h,Cmax=46.65±4.9μg@mL-1,t1/2=5.44h,k=0.127h and AUC0-t=256.91(μg·min·nL-1),AUC0-∞=290.52(μg·rmin·mL-1).结论本方法为滋肾丸中肉桂酸的血药浓度监测及药动学研究提供了方法学基础.     

A Comparison of the Inflammatory Response of the Lung to Inhaled versus Instilled Particles in F344 Rats

The potential pulmonary toxicity of poorly soluble airbornedusts generated in industrial and environmental settings isoften evaluated by inhalation studies in rodents. Studies usingintra tracheal instillation of particles have been suggestedas a less expensive alternative. We conducted a study to comparethe inflammatory response of the lung to instilled versus inhaledparticles. In one study, female F344/N rats, 11/13 weeks ofage, were exposed for 6 hr/day, 5 days/week for 4 weeks by inhalationto O, 0.1, 1.0, or 10 mg/m³ of either ß-quartz (toxicparticle) or TiO² (relatively low toxicity particle) and thelung burdens were determined at 1 week after the end of theexposure. The lungs were evaluated by analysis of bronchoalveolarlavage fluid (BALF) at 1, 8, and 24 weeks after the end of theexposure and by histopathology at 24 weeks. In a second study,rats were exposed by instillation to the lung burdens presentin the preceding study at 1 week after the inhalation exposure,and the rats were evaluated in the same manner as in the inhalationstudy. In general, the degree of alveolitis, as evaluated byhistopathology and BALF analysis, was similar by the two methodsof exposure. With lung burdens up to 750 µ/g, lung, theTi0² elicited no changes in BALF parameters at any time by eithermethod of exposure, nor was any histopathology observed. TheBALF changes elicited by -quartz were of approximately the samemagnitude and followed the same time course by either exposuremethod with the lowest dose delivered to the lung by eithermethod being a "no-effect" dose. At the highest dose, microgranulomaswere observed in bronchial-associated lymphoid tissue (BALT)in both sets of rats. However, the highest inhalation exposureinduced pleural granulomatous lesions that were not observedin the animals instilled with -quartz. The results indicatethat the relative potentials of the two materials to producebronchoalveolitis and granulomatous lesions in BALT could beappropriately evaluated using either intratracheal or inhalationexposures.     

Ethylene Dichloride: The Influence of Disulfiram or Ethanol on Oncogenicity, Metabolism, and DNA Covalent Binding in Rats

Ethylene Dichloride: The Influence of Disulfiram or Ethanolon Oncogenicity, Metabolism, and DNA Covalent Binding in Rats.CHEEVER, K. L., CHOLAKJS, J. M., EL-HAWARI, A. M., KOVATCH,R. M., AND WEISBURGER, E. K. (1990) Fundam. Appl. Toxicol 14,243–261. Male and female Sprague-Dawley rats were exposedto 50 ppm ethylene dichloride (EDC) for 7 hr/ day, 5 days/week,for 2 years by inhalation. Additional rats were exposed to 50ppm EDC either with 0.05% disulfiram in the diet or with 5%ethanol in the drinking water. Histopathologic lesions relatedto the combination of inhaled EDC and dietary disulfiram wereobserved in the liver, mammary, and testicular tissues of rats.This combined exposure resulted in a significant increase inthe incidence of intrahepatic bile duct cholangiomas in bothmale and female rats. Male rats exposed to both EDC and disulfiramalso had an increased incidence of subcutaneous fibromas, neoplasticnodules, and interstitial cell tumors in the testes. The femalerats exposed to EDC and disulfiram also had a higher incidenceof mammary adenocarcinomas. No significant increase in the numberof any tumor type was observed in rats exposed to only EDC,disulfiram, or ethanol. Similarly, no significant increase inthe number of tumors was observed in rats exposed to inhaledEDC and ethanol in water. At the end of the 2-year period animalsfrom each group were evaluated for EDC metabolism and DNA binding.Blood levels of EDC at the end of a 7-hr exposure period weresignificantly higher for rats exposed to both EDC and disulfiramthan for rats exposed to EDC alone. In addition, the eliminationof a single oral dose of radiola-beled EDC was affected. Theurinary excretion of I4C from control rats was 47 to 55% ofthe administered dose with 28 to 30% detected as unchanged EDCin the breath. In disulfiram-treated rats, only 35 to 36% ofthe administered I4C was eliminated in the urine with 41 to55% as unchanged EDC in the breath. The urinary metabolite HPLCprofile was qualitatively unchanged by long-term EDC, disulfiram,or ethanol treatment, either alone or in combination, and consistedprimarily of thiodiglycolic acid, thiodiglycolic acid sulfoxide,and chloroacetic acid.     

高效液相色谱-电化学法测定大鼠不同脑区的单胺类神经递质

目的:建立同时测定大鼠脑组织中单胺类神经递质去甲肾上腺素(NE)、多巴胺(DA)和5-羟色胺(5-HT)的高效液相色谱-电化学检测法(HPLC-ECD).方法:采用Diamonsil C18柱,以Na2HP04-枸橼酸-EDTA-庚烷磺酸钠-甲醇-水(80:40:2:7:32:89)为流动相,流速:1.2 ml/min.大鼠脑组织样品经高氯酸沉淀除去蛋白后,电化学检测脑内NE、DA和5-HT的含量.结果:脑组织中NE、5-HT的线性范围为0.50～10.00 ng,DA的线性范围为0.25～30.00ng.脑组织样品的相对回收率为91.7%～110.2%,日内、日间变异均小于15%.经初步研究,正常雄性SD大鼠不同脑区内NE、DA和5-HT的含量分别为伏隔核(508±203)、(3140±486)、(601±105)ng/g,腹侧被盖区(695±152)、(746±143)、(1049±222)ng/g,下丘脑(2032±351)、(332±236)、(847±218)ng/g,纹状体(790±205)、(5816±805)、(538±112)ng/g.结论:该方法具有准确、灵敏、样品制备简便等优点,可用于大鼠部分脑区内单胺类神经递质的分离测定.