氮烯乙茶在成年大鼠肝细胞中的生物转化

目的:建立成年大鼠肝细胞分离培养方法,探讨抗癌新药氮烯乙茶在肝细胞内生物转化。方法:用肝细胞活率、乳酸脱氢酶、能荷值变化观察肝细胞悬浮培养方法的稳定性,以高效液相色谱法测定肝细胞悬液中氮烯乙茶及其代谢产物的浓度。结果:氮烯乙茶在大鼠肝细胞内生成代谢产物7-乙基-8-氨基茶碱(7-ethyl-8-aminotheophylline,EAT) ,其最大反应速度Vm 为12-80 nmol·min^-1/106 cells,米氏常数Km 为640-9 μmol·L^-1 ,氮烯乙茶的固有清除率CLint为20-0 μL·min^-1/106 cells。结论:肝细胞培养的方法是考察药物生物转化的较好体外模型,同时氮烯乙茶具有降低肝细胞能荷值的作用。     

氮烯乙茶在大鼠、犬、猴肝亚细胞成分中的生物转化

目的:利用肝亚细胞成分研究I类抗癌新药氮烯乙茶的生物转化及其种属差异。方法:以高效液相色谱法检测肝9 000 ×g 上清液(S-9) 和微粒体中氮烯乙茶及其代谢产物的浓度。结果:大鼠、犬、猴肝S-9中氮烯乙茶的固有清除率(CL_int) 分别为14-9,10-4,30-4 μL·min^-1·mg^-1 protein,代谢产物为7-乙基-8-氨基茶碱(7-ethyl-8-aminotheophylline,EAT),氮烯乙茶在肝的生物转化部位在微粒体。结论:预计氮烯乙茶在生物转化途径上的种属差异较小;肝亚细胞成分是研究药物代谢及种属差异的较好体外模型。     

催醒宁在大鼠离体灌流肝脏中的生物转化

用离体大鼠肝脏灌流方法,研究了胆碱酯酶抑制剂CXN的生物转化过程。径HPLC分离纯化及光谱分析,鉴定了CXN的六个脂溶性代谢产物的化学结构。产物Ⅰ为CXN原形,其余均为氧化产物。其中产物Ⅲ尚保留部分抑酶活力,而产物Ⅱ,Ⅴ及Ⅵ对小鼠全脑胆碱酯酶的抑酶活力明显下降。另外还观察到,代谢产物Ⅱ及Ⅴ对小鼠的急性毒性也明显减小。     

离体大鼠肝脏延长灌流

<正> 在药理或毒理研究中,一般采用短时间(2h之内)离体大鼠肝脏灌流,由于正常肝脏活性维持的时间短,应用于许多实验受到限制,远不能满足需要。本文研究了离体大鼠肝脏的延长灌流,自行设计灌流装置,改进了氧合器等装置,选择了能使灌流时间延长的合适灌流体系。 离体大鼠肝脏在5h的灌流中,灌流液中各项指标观察结果是:pH7.55～7.36,PO_2 227～272 mmHg,O_2含量7.4～7.6 Vol％,O_2饱和度99.2～99.7％,PCO_2 40.8～41.5 mmHg,K~+ 6.0～8。8 mM,Na     

大鼠离体肝脏灌流系统的建立

目的：建立大鼠离体肝动脉／门静脉灌流系统的实验方法。方法：雌性Wistar大鼠麻醉状态下,肝动脉、门静脉和肝静脉插管;经肝动脉冲净残留血液,灌流状态下游离肝脏;定量蠕动泵调节肝动脉或门静脉的Krebs—Henseleit平衡液（或加等渗葡聚糖）的灌流流速,泰盟BL-420S生物机能实验系统监测肝动脉或门静脉的压力变化,采用Prism-4非线型可变斜率回归获得“有或无胶体渗透压”KH液灌流的流速-压力曲线及方程式,计算半效流速及其95％的可信限。结果：无胶体渗透压灌流状态下的肝脏系数无差别,肝动脉的半效流速为2217（95％CI1209～4068）μl·min^－1,对数流速-压力直线方程为Y=142．4x＋706．9;门静脉半效流速为3791（95％CI3549～4049）μl·min^－1,对数流速-压力直线方程为Y：479．6X＋5034。等效胶体渗透压灌流状态下的肝脏系数无差别,肝动脉半效流速为3754（95％CI3175～4440）μl·min^－1,对数流速-压力直线方程为Y=133．5X-719．0;门静脉半效流速为6018（95％CI5565—6508）μl·min^－1,对数流速-压力直线回归方程为Y：538．3X4-4704。半效流速接近正常大鼠生理平均值,各半效流速95％可信限涵盖大鼠正常生理状态的变化范围。有或无胶体渗透压灌流状态之间总体无差别。结论：在恒流测压模式下,等渗灌流大鼠离体肝动脉和门静脉灌流系统的视窗时程长、机能变化稳定、操作流程简便,为认识肝动脉和门静脉离体舒缩机制奠定了基础。     

大鼠离体肝脏灌流方法的改良

<正> 离体肝脏灌流(isolated liver perfusion,ILP)广泛用于药理毒理学研究,尤其在药物代谢研究方面日益受到重视。本文研究了ILP方法的改良对大鼠肝脏功能影响。常规应用的Krebs—Hcnseleit灌流液均加红细胞和血清白蛋白,这给药物的分离测定带来困难。本文用右旋糖酥代替白蛋白以维持胶渗,浓度为1.5％,并适当提高灌流速度以弥补供氧不足,流速约2～3ml·min~(-1)·g~(-1)(liver)。为减少肝脏损害,简化了手术程序,只做门静脉插管,不做下腔静脉插管及肾静脉结扎,缩短了手术时间。肝功能检查发现,灌流2h后,灌流液中LDH,     

1—硝基芘在离体灌流肺中的生物转化及消除：大鼠比苯马比妥,β—萘…

将１５０μｇ１－硝基芘气管内或血管内给药后，对大鼠离体肺进行灌流，定时自灌流液中取样，以ＨＰＬＣ和ＧＣ－ＭＳ测定并鉴定灌流液中未变的１－ＮＰ及代谢物。经鉴定代谢物为单羟基硝基芘和二羟基硝基芘。两种途径给药后，１－ＮＰ在灌流液中的浓度－时间数据条例一室药代动力学模型。     

一过性离体大鼠肝脏灌流模型的建立

目的利用UP-100通用灌流仪建立了一过性离体大鼠肝脏灌流模型。方法用Krebs-Henseleit碳酸氢盐缓冲液进行一过性离体大鼠肝脏灌流,在灌流时长90 min内通过检测AST、ALT和LDH的浓度,观察肝脏外观及胆汁流量,测定肝重变化,进行组织切片观察组织病理变化来评估离体灌流肝脏的损伤程度。结果 90 min灌流时长中,肝脏颜色质地正常,胆汁流量均匀,相应转氨酶释放量少,病理切片结果正常。结论离体大鼠肝脏在UP-100通用灌流仪90 min灌流过程中能保持较好的组织结构和肝脏功能,可用于离体肝脏的药物代谢研究。     

离体大鼠肝脏灌流技术及其在植物药研究中的应用进展

离体大鼠肝灌流技术是肝脏灌流技术应用最广泛的一种.该模型兼备体外实验和整体动物实验的优点,被广泛应用在药物代谢,药物相互作用,胆汁分泌等研究中.本文对离体大鼠肝灌流技术及其在植物药研究中的应用进展进行了综述.     

离体大鼠肝脏灌流技术及其在植物药研究中的应用进展

离体大鼠肝灌流技术是肝脏灌流技术应用最广泛的一种。该模型兼备体外实验和整体动物实验的优点,被广泛应用在药物代谢、药物相互作用、胆汁分泌等研究中。本文对离体大鼠肝灌流技术及其在植物药研究中的应用进展进行了综述。     

抗痫灵在大鼠肝脏中代谢的研究

用离体大鼠肝脏灌流法,研究了抗痫灵在肝脏灌流过程中的代谢规律。用高效液相色谱法由灌流液中分离、制备得到了两种代谢物,经紫外吸收光谱与质谱鉴定,确定代谢物的结构为3,4-次甲基二氧桂皮酰羟基哌啶及阿魏酰哌啶,后者经化学合成得到了进一步的确证。本文还研究了肝循环过程中抗痫灵的代谢动力学,揭示了大部份抗痫灵以原形结合贮存于肝脏中。     

抗痫灵在大鼠肝脏中代谢的研究

用离体大鼠肝脏灌流法,研究了抗痫灵在肝脏灌流过程中的代谢规律。用高效液相色谱法由灌流液中分离、制备得到了两种代谢物,经紫外吸收光谱与质谱鉴定,确定代谢物的结构为3,4-次甲基二氧桂皮酰羟基哌啶及阿魏酰哌啶,后者经化学合成得到了进一步的确证。本文还研究了肝循环过程中抗痫灵的代谢动力学,揭示了大部份抗痫灵以原形结合贮存于肝脏中。     

INHIBITION BY SALICYLATE OF GLUCONEOGENESIS IN THE ISOLATED PERFUSED RAT LIVER

SUMMARY 1. Sodium salicylate has been used as a hypoglycaemic agent in the treatment of diabetic patients and severe hypoglycaemia has been reported in children treated with aspirin. The mechanism of this hypoglycaemic action has never been elucidated.
2. In the isolated perfused rat liver, salicylate inhibits gluconeogenesis from lactate, alanine and propionate. The degree of inhibition is related to salicylate concentration and occurs with 2 mM (30 mg/100 ml).
3. The inhibitory action probably results from the effect of salicylate on oxidative phosphorylation in that there was little or no inhibition of gluconeogenesis from precursors which do not have a high requirement for ATP in their metabolism to glucose.
4. In man, lactate and alanine are the main precursors of glucose, and the liver is the main site of gluconeogenesis. These results demonstrate a mechanism for salicylate induced hypoglycaemia in man, and in addition suggest that accumulation of lactate may account for the acidosis sometimes produced by overdosage with salicylate.     

SENSITIVITY OF PROPRANOLOL ELIMINATION TO HYPOXIA IN THE ISOLATED PERFUSED RAT LIVER PREPARATION

1. The relationship between the hepatic elimination of propranolol and hepatic oxygen delivery was examined in the single-pass isolated perfused rat liver preparation. Varying rates of oxygen delivery were produced (1.35–8.10 μmol/min per g liver) by equilibrating the perfusate with O₂/N₂ mixtures. 2. In two experiments, in which the rate of oxygen delivery was increased or decreased within the hypoxic range (< 4–5 μmol/min per g liver) every 5 min for 120 min, propranolol clearance responded very rapidly in the same direction as the change in oxygen delivery. 3. In five experiments, propranolol clearance, measured at steady state during an initial 30 min normoxia phase and three subsequent 30 min hypoxia phases (oxygen delivery in the range 1.35–5.89 μmol/min per g liver), was linearly related to hepatic oxygen delivery and consumption (r= 0.92 ± 0.07). 4. These data, combined with those from six further experiments that used one normoxia phase followed by one hypoxia phase, showed that there was a threshold for oxygen delivery of about 6 μmol/min per g liver, below which propranolol clearance decreased with decreasing oxygenation. 5. This study shows that in the intact liver propranolol elimination is very sensitive to hepatic oxygen supply, with impairment in clearance occurring at the lower limit of what is considered normal hepatic oxygenation in the rat.     

EFFECTS OF ALBUMIN ON THE DISPOSITION OF MORPHINE AND MORPHINE-3-GLUCURONIDE IN THE RAT ISOLATED PERFUSED LIVER

1. The effect of albumin on the disposition of morphine and hepatically generated morphine-3-glucuronide (M3G) was investigated in the single-pass rat isolated perfused liver. 1. Interest in the pharmacokinetic and pharmacodynamic properties of the enantiomers of chiral drugs has greatly increased in recent years. This is particularly so for agents used in anaesthesia. 2. Chiral compounds are those that can exist in two non-superimposable forms. Each form is termed an enantiomer or stereoisomer. Two naming systems are in use: one uses the terms (+) and (–) to indicate the direction the compound will rotate polarized light, while the other system, based on the absolute three-dimensional structure of the enantiomers, uses the terms R and S. 3. Investigation of the stereoisomers of the volatile anaesthetic agent isoflurane is increasing our understanding of the mechanism of general anaesthesia. Current evidence suggests a protein, rather than a lipid, receptor site. 4. Investigation of the stereoisomers of local anaesthetics is increasing the safety of these drugs. 5. For bupivacaine, a widely used amide local anaesthetic, important enantiomeric differences can be found for toxicity, clinical effect and pharmacokinetics. In particular S-(–)-bupivacaine has an improved central nervous system and cardiac safety profile. This is partly explained by the pharmacokinetic differences. 6. Based on these differences, ropivacaine, a propyl homo-logue of bupivacaine, has been produced solely as the S-(–)-enantiomer. The available evidence suggests significantly improved safety for this agent over racemic bupivacaine.     

EFFECTS OF DOPAMINE ON RENAL FUNCTION IN THE RAT ISOLATED PERFUSED KIDNEY

The renal effects of dopamine, the dopamine antagonist spiperone and the combination of dopamine and spiperone were examined in the isolated perfused rat kidney preparation. Studies were carried out at constant perfusion pressure and the following were measured at 10 min intervals for 1 h: perfusate flow; GFR (3H-inulin); urine flow rate; sodium, potassium and kallikrein excretion; perfusate renin concentration; perfusate and urinary-dopamine levels. Low-dose dopamine infusion (6 X 10(-10) mol/min) resulted in significant diuresis, natriuresis and kaluresis but little change in GFR. These effects were blocked by spiperone (10(-10) mol/min) which had no significant effects when infused alone. At a higher dose (10(-8) mol/min) dopamine significantly increased urine flow alone; this too was reversed by spiperone. Dopamine had no significant effects on perfusate flow, renin release or kallikrein excretion. Perfused control kidneys excreted amounts of dopamine (328 pmol/h, s.e.m. = 57, n = 6) far in excess of kidney dopamine content (49 pmol/g, s.e.m. = 6, n = 32). Renal handling of infused dopamine was dose-related; the fraction of the administered dose taken up and/or metabolized by the kidney on the higher dose infusion was considerably less than on the lower dose (40%, s.e.m. = 3 vs. 82%, s.e.m. = 6) while more was excreted (13%, s.e.m. = 3 vs. 2%, s.e.m. = 1). These studies indicate that dopamine at low doses can produce diuresis, natriuresis and kaluresis independently of extrarenal or haemodynamic influences and not mediated by renal renin or kallikrein systems. The kidney also exhibits a saturable capacity for dopamine uptake and/or metabolism.     

EFFECTS OF OPIATES ON SODIUM EXCRETION IN THE ISOLATED PERFUSED RAT KIDNEY

1. A rat isolated perfused kidney preparation was utilized to define clearly a renal site of action. The variables measured were perfusate pressure and flow, glomerular filtration rate, urine volume, sodium excretion and potassium excretion. 2. Dextromethorphan (3 nmol/L) and dextrorphan (10 nmol/L) reduced sodium excretion in kidneys from rats on either control or high K+ diet, in the absence of any other measured renal effects. Dextromethorphan (10 nmol/L) produced a decrease in glomerular filtration rate as well as a decrease in sodium excretion. Naloxone (1 mumol/L) inhibited the effect of dextromethorphan on sodium excretion but had no effect when administered alone. 3. The levorotatory opiates levorphanol and levomethorphan, the kappa agonist ketocyclazocine and a range of other opiates had no effect on sodium excretion. 4. The results suggest a renal action specific for dextrorotatory opiates. This renal action is consistent with earlier binding studies suggesting preferential recognition of dextrorotatory opiates.