Molecular aspects of catechol and pyrogallol inhibition of liver microsomal lipid peroxidation stimulated by ferrous ion-ADP-complexes or by carbon tetrachloride

Summary Lipid peroxidation was induced in rat liver microsomes either by iron-ADP-complexes or by carbon tetrachloride in the presence of NADPH. Different compounds containing catechol or pyrogallol structures were examined for their activities to inhibit lipid peroxidation in both systems. In general, all compounds tested showed similar inhibitory activities on lipid peroxidation, if induced by ferrous ion-ADP-complexes or by carbon tetrachloride. This inhibition is explained by the suggestion that catechols and pyrogallos inhibit at the lipid site of the membrane, rather than at the enzymic site. Compounds not containing catechol or pyrogallol groups inhibited lipid peroxidation only weakly. O-Methylation resulted in a decrease of the inhibitory effect. Catecholor pyrogallol-derivatives which contained polar functional side chains, like carboxyl- or amino groups showed minor inhibitory effects compared to the esterified or N-alkylated compounds.Dihydroxychlorpromazine, 2-hydroxy-estradiol and 2-hydroxyethinylestradiol were the most effective inhbitors of microsomal lipid peroxidation (I₅₀-values of 1×10^–6 to 2×10^–7 M). The inhibitory activity of -tocopherol, glutathione and ascorbic acid, naturally occurring antioxidants, was about three orders of magnitude lower.Inhibition of lipid peroxidation induced by NADPH-cytochrome c reductase and iron-ADP-complexes in the presence of NADPH and liposomes was also observed with catechols.From our results we assume that the molecular structure of a catechol or pyrogallol functional group is a prequisite for an effective inhibition of lipid peroxidation by these chemicals. Furthermore, the results are discussed in relation to the requisite membrane affinity of catechols, pyrogallols and other antioxidants which might be used for inhibition studies on lipid peroxidation in vivo.     

Cardiac sensitization induced by phenobarbitone and prolonged by CS2

The arrhythmogenic effect of 8 g/kg noradrenaline given i.v. was increased in male rats pretreated 1–2 day s earlier with phenobarbitone and starved from the time of the first phenobarbitone injection (80 mg/kg followed by 50 mg/kg 6 h later). Daily exposure to 4.0 mg/l CS₂ (first exposure 24 h after the first phenobarbitone injection) for 4 h prevented the decline in susceptibility on the 3rd and 4th days after phenobarbitone, when the reaction of unexposed rats to noradrenaline returned to normal.     

慢肝养阴胶囊对肝损伤模型保护作用的实验研究

目的 :研究慢肝养阴胶囊的主要药理作用。方法 :观察对四氯化碳引起的大鼠慢性肝损伤的影响 ;观察对小鼠肝郁脾虚的功能影响 ;观察小鼠对化学物质引起的急性肝损伤的影响及对免疫功能的影响。结果 :慢肝养阴胶囊对由四氯化碳所致的大鼠慢性肝损伤有明显的保护作用 ,对D 半乳糖胺盐酸盐急性肝损伤的保护作用明显 ,对由四氯化碳所致肝郁脾虚小鼠肝中甘油三酯和胆固醇含量有明显的降低作用 ;对注射环磷酰胺所致的免疫功能低下有一定的增强作用 ,提高廓清指数 (K)与模型组比较差异有显著性意义 (P <0 0 5 )。结论 :慢肝养阴胶囊具有明显的保肝护肝 ,滋补肝肾的功效。     

一氧化碳和一氧化氮在新生儿缺氧缺血性脑病发病中的作用

目的：探讨一氧化碳（ＣＯ）和一氧化氮（ＮＯ）在新生儿缺氧缺血性脑病（ＨＩＥ）中的作用。方法：对２８例新生儿ＨＩＥ血浆ＣＯ和ＮＯ水平进行检测，并与３０例正常新生儿对照组比较。结果：与正常对照组比较，２８例新生儿ＨＩＥ患儿血浆ＣＯ、ＮＯ水平显著增高；与轻、中度新生儿ＨＩＥ患儿比较，重度者血浆ＣＯ、ＮＯ水平显著增高；ＣＯ和ＮＯ呈显著正相关。结论：ＣＯ和ＮＯ在新生儿ＨＩＥ的发病过程中具有重要意义。     

白首乌茎叶总黄酮对小鼠急性化学性肝损伤的保护作用

目的:研究白首乌茎叶总黄酮(TFC)对小鼠急性化学性肝损伤的保护作用。方法:腹腔注射四氯化碳(CCl4)制备小鼠急性肝损伤模型,检测血清丙氨酸氨基转移酶(ALT)和天门冬氨酸氨基转移酶(AST)活性、肝脏重量指数;同时测定肝组织中丙二醛(MDA)、一氧化氮(NO)含量和超氧化物歧化酶(SOD)活性。结果:连续7d灌胃给予10,20mg/(kg·d)白首乌茎叶总黄酮,能明显抑制肝损伤小鼠血清ALT和AST活性的升高(P<0.01),减轻增加的肝脏重量指数,显著抑制肝组织中MDA和NO含量的升高及SOD活性的下降(P<0.01)。结论:白首乌茎叶总黄酮对CCl4引起的小鼠急性肝损伤具有保护作用,这种作用与其抗脂质过氧化有关。     

Precision-cut liver slices as a new model to study toxicity-induced hepatic stellate cell activation in a physiologic milieu.

Hepatic stellate cell (HSC) activation is a key event in the natural process of wound healing as well as in fibrosis development in liver. Current in vitro models for HSC activation contribute significantly to the understanding of HSC biology and fibrogenesis but still fall far short of recapitulating in vivo intercellular functional and anatomic relationships. In addition, when cultured on uncoated plastic, HSC spontaneously activate, which makes HSC activation difficult to regulate or analyze. We have examined whether the use of precision-cut liver slices might overcome these limitations. Liver slices (8 mm diameter, 250 microm thickness) were generated from normal rat liver and incubated for 3 or 16 h with increasing doses of carbon tetrachloride (CCl4). Rat liver slices remained viable during incubation, as shown by minimal enzyme leakage. Expression of markers for HSC activation and the onset of fibrogenesis in the liver slices was studied using real-time PCR and Western blotting. In unstimulated liver slices, mRNA and protein levels of desmin, heat shock protein 47, and alpha B-crystallin remained constant, indicating quiescence of HSC, whereas Krüppel-like factor 6 expression was increased. In contrast, incubation with CCl4 led to a time- and dose-dependent increase in mRNA expression of all markers and an increased alpha B-crystallin protein expression. In conclusion, we have developed a technique to induce activation of quiescent HSC in rat liver slices. This model permits the study of toxicity-induced HSC activation within a physiological milieu, not only in animal but ultimately also in human tissue, and could contribute to the reduction of animal experiments.     

The contracting and relaxing responses of human internal mammary artery grafts harvested by two different methods

Perioperative spasm of internal mammary artery is a common experience in coronary artery bypass grafting. Many techniques were described of harvesting the internal mammary artery to prevent vasospasm. We investigated the comparison of the contracting and relaxing responses of human internal mammary artery grafts harvested by two different methods. Patients were divided into two groups depending on the harvesting technique. In the first and second groups arteries were harvested by classical and carbon dioxide insufflation techniques, respectively. In both groups, endothelial function of arteries was assessed by precontracting the rings with phenylephrine (10(-5)M) and dilatating them by cumulative acetylcholine (10(-8) to 10(-5)M) concentrations. Cumulative concentration-response curves for phenylephrine (10(-8) to 10(-4)M), noradrenaline (10(-9) to 10(-4)M), and 5-hydroxytryptamine (10(-9) to 10(-4)M) were obtained in all groups. Endothelial integrity of arteries were histopathologically evaluated. In both groups, acetylcholine caused concentration-dependent relaxations in rings precontracted with phenylephrine (10(-5)M). In arteries harvested by carbon dioxide insufflation technique, acetylcholine caused significantly higher relaxations compared to the rings obtained by classical technique (p<0.05). In all rings of study groups, phenylephrine, noradrenaline and 5-hydroxytryptamine caused concentration-dependent contractions. There was not any significant difference in concentration-dependent responses of these contracting pharmacological agents between the groups. Histopathological evaluation revealed no major arterial damage in both groups. Carbon dioxide insufflation technique does seem not only to protect the integrity of the endothelium and the whole vessel, but also prevent the possible vasospasm of the internal mammary artery segments.     

赤芍水提物对四氯化碳致肝损伤大鼠的保护作用

目的：探讨赤芍水提取物对四氯化碳(CCl4)中毒性肝纤维化大鼠的治疗作用。方法：复制大鼠CCl4肝纤维化模型，以马洛替酯为阳性对照，采用光镜观察组织学改变， 测定血清丙氨酸氨基转移酶(ALT)、天门冬氨酸氨基转移酶(AST)、一氧化氮(NO)、透明质酸(HA)、层粘蛋白(LN)，肝组织羟脯氨酸(Hyp)、丙二醛(MDA)以反映肝细胞损伤及肝纤维化的程度。结果：赤芍水提物能降低实验性肝纤维化大鼠血清中升高的ALT、AST、NO、HA、LN水平和肝组织中过高的Hyp、MDA的含量。病理组织学检查亦表明，赤芍水提物明显改善实验性肝纤维化。结论：赤芍水提物对实验性肝纤维化具有治疗作用。     

二硫化碳对小鼠心肌细胞肌浆网Ca2+-ATP酶基因表达的影响

目的探讨二硫化碳(CS2)对小鼠心肌细胞肌浆网Ca2 -ATP酶(SERCA2 a)表达的影响机制。方法将48只昆明小鼠分为4组给予不同剂量CS2(0~800 mg/m3)吸入染毒5周后,提取心肌的总RNA,运用逆转录聚合酶链反应技术来检测染毒小鼠心肌细SERCA2 a表达水平的变化。结果染毒前后体重差异无显著性(P>0.05),随着染毒剂量的增大,小鼠心肌细胞SERCA2 a的表达逐渐降低,与对照组比较差异有显著性(P<0.05)。结论CS2能降低小鼠心肌SERCA2 a的mRNA表达水平。     

10%四氯化碳致大鼠慢性肝损伤的研究

目的：研究10％四氯化碳致大鼠慢性肝损伤中间病理变化，为建立10％四氯化碳慢性肝损伤模型提供实验依据。方法：雄性Wistar大鼠80只，随机分为正常对照组和实验组。每组动物各40只。正常对照组腹腔注射玉米油，0．1ml／100g．bw；实验组腹腔注射10％四氯化碳，0．1ml／100g．bw。于实验期的第1、3、6和8周，两组动物分别腹腔注射玉米油和四氯化碳后48h放血处死，取肝组织作组织病理学观察。结果：实验组染毒1周后，肝小叶中央静脉周围大量细胞脂肪变性，肝小叶中央区有少量细胞气球样变；实验组染毒3周后，肝小叶中央静脉周围大量细胞脂肪变性，肝小叶中央区有少量细胞气球样变；实验组染毒3周后．肝小叶中央静脉周围大量细胞脂肪变性，肝小叶中央区有少量细胞气球样变；实验组染毒3周后，肝小叶中央静脉周围肝细胞气球样变加重；实验组染毒6周后，肝小叶中央静脉周围开始出现少量细胞坏死；实验组染毒第8周后，出现肝纤维化，未达到肝硬化。结论：建议少用该模型鉴定药物和保健食品对慢性肝损伤的保护作用。