腐胺对大鼠心肌缺血再灌注损伤的保护作用

目的 :观察腐胺对大鼠心肌缺血再灌注损伤的保护作用。方法 :利用 Langendroff- Neely离体心灌注方法 ,以缺血 12 0 min,再灌注 2 0 min制备大鼠心肌缺血再灌注损伤模型。对照组 (n=12 ) ,采用St.Thomas液作为心停搏液。实验组 (n=12 )以腐胺 10 mg/ ml作为心停搏液 (St.Thomas液 )的添加剂。测定心脏停搏前和缺血 12 0 min,再灌注 2 0 min后的心率、主动脉流量、冠脉流量和心输出量。测定心脏缺血 12 0 min,再灌注 2 0 min后心肌组织 MDA、SOD,并进行心肌超微结构比较研究。结果 :实验组较对照组心功能改善 ,缺血再灌注损伤心肌 SOD活性无明显变化 ,明显降低缺血再灌注损伤心肌MDA水平 ,减轻细胞膜结构的损害 ,心肌水肿程度明显减轻 ,心肌结构保存好。结论 :腐胺对大鼠心肌缺血再灌注损伤具有保护作用     

多胺代谢与大鼠心肌缺血再灌注损伤关系的实验研究

目的 观察缺血再灌注不同时期大鼠心肌多胺代谢变化规律,探讨多胺代谢与心肌缺血再灌注损伤的关系.方法 采用结扎冠状动脉方法复制大鼠在体心肌缺血再灌注损伤模型,应用逆转录聚合酶链反应(RT-PCR)、Western免疫印迹(Western blot)方法分别测定正常、缺血再灌注2 h、6 h、12 h和24 h时心肌鸟氨酸脱羧酶(ODC)和精胺/精脒乙酰转移酶(SSAT)mRNA的转录和蛋白表达水平,并用高效液相色谱仪测定多胺含量变化.结果 心肌缺血再灌注后ODC和SSAT mRNA的转录和蛋白表达均上调,至再灌注24 h时,与假手术组比,ODC mRNA和SSAT mRNA转录分别增加了3.1倍和3.8倍(P＜0.01),ODC和SSAT的蛋白表达分别增加了3.1倍和2.9倍(P＜0.01).精胺、精脒和多胺总代谢池含量减少,至再灌注24 h时,分别比假手术组少了33.6%、35.3%和32.9%,而腐胺多了58.9%(P＜0.01).结论 心肌缺血再灌注损伤可导致多胺代谢失衡,二者密切相关.     

丹栀逍遥散对D-氨基半乳糖/脂多糖诱导的大鼠急性肝损伤保护作用机制研究

目的 探讨丹栀逍遥散对D-氨基半乳糖(D-GaIN)/脂多糖(LPS)诱导的大鼠急性肝损伤(ALI)的保护作用及其可能的作用机制.方法 将110只SD大鼠随机分为对照组、模型组、小剂量、中剂量和大剂量丹栀逍遥散干预组,每组22只.采用D-GaIN)/LPS腹腔注射建立ALI模型,分别给予生理盐水或药物灌胃干预.采用EL...     

Changes of hepatic fatty acid metabolism produced by chronic thioacetamide administration in rats.

Hepatic mitochondrial functions related to fatty acid metabolism, including the respiratory control ratio, fatty acid oxidative capacity and carnitine palmitoyltransferase I activity, were studied in vitro with mitochondria isolated from rats treated with thioacetamide for up to 12 wk. The levels of ketone bodies, carnitine, carnitine esters and malonyl-coenzyme A were also determined in liver extracts. Polarography of mitochondrial respiration from succinate or glutamate plus malate showed a lower respiratory control ratio in thioacetamide-treated rats, whereas uncoupled oxygen consumption was not altered. This suggests that the mitochondrial respiratory chain capacity remained intact in the thioacetamide-treated rats. The oxygen consumption associated with palmitoyl-coenzyme A and palmitoyl-L-carnitine oxidation by isolated liver mitochondria was increased by thioacetamide treatment on both a per-mitochondrial protein and a per-total liver basis. The carnitine palmitoyl-transferase I activity; the tissue levels of ketone bodies, carnitine and carnitine esters; and the beta-hydroxybutyrate/acetoacetate ratio were all higher in the livers of thioacetamide-treated animals than in control livers, whereas the hepatic malonyl-coenzyme A level was decreased by thioacetamide. These results indicate the increased diversion of cytosolic long-chain acyl-coenzyme As into the mitochondria for beta-oxidation rather than their esterification and use in lipogenesis. These intrahepatic metabolic changes induced by chronic thioacetamide administration may reflect the whole-body catabolic state and can be seen as adaptive for maintaining energy homeostasis under conditions of impaired glucose tolerance.     

Protective effects of fibronectin in galactosamine-induced liver failure in rats

The effects of supplementation with fibronectin on liver damage and survival in rats with galactosamine-induced liver failure were studied. In rats with acute liver failure induced by a low dose of galactosamine, supplementation with purified plasma fibronectin at 3 hr after the administration of galactosamine provided significant increase of plasma fibronectin levels and augmentation of reticuloendothelial system function at 4 hr, significantly higher plasma fibronectin levels and significant protection of liver damage with shorter prothrombin times, lower AST and less histological damage at 48 hr as compared to control animals. Plasma fibronectin levels were inversely correlated with both plasma prothrombin times and AST. Fibronectin supplementation at 6 hr also resulted in the significant decrease of liver damage at 48 hr as evaluated histologically. When rats with liver failure, induced by a high dose of galactosamine, were supplemented with fibronectin at 3 hr, the survival rate was significantly higher than that of control rats. The results indicate that fibronectin supplementation in the early stages of acute liver failure could reduce liver damage and improve the survival of rats with galactosamine-induced liver failure.     

Changes in glycoproteins of liver plasma membranes from rats treated with D-galactosamine.

D-Galactosamine administration to rats (400 mg/kg) by intraperitoneal injection induced biochemical alterations in liver plasma membranes. Alterations were studied 4, 16 and 24 h after D-galactosamine injection. Plasma membrane 5'-mononucleotidase activity decreased to 40% of control values. Carbohydrate composition was significantly changed. After 24 h D-galactosamine administration, the diminution in plasma membrane sialic acids and hexoses reached 30% of control values. As detected by SDS-acrylamide gel electrophoresis, high molecular weight glycoproteins of D-galactosamine-treated plasma membranes were modified. Moreover, the incorporation of [35S]-sulfate into membrane glycoproteins decreased after D-galactosamine administration (40--60% of control). The present results show that biochemical alterations in rat liver plasma membranes appear soon after D-galactosamine injection. Marked changes are observed in cell surface glycoproteins, especially in sialoglycoproteins and sulfated glycoproteins.     

Effect of bile acids on hepatic protoporphyrin metabolism in perfused rat liver

To determine the effect of bile acids on hepatic protoporphyrin metabolism, balance studies were performed in isolated perfused rat livers. Hepatic protoporphyrin metabolism was found to increase linearly as a function of protoporphyrin dose in livers infused with and without taurocholate (0.7 mumol/min), but their rates differed significantly. Employing a standard 1500-nmol protoporphyrin bolus dose, infusions (0.7 mumol/min) of taurocholate, glycocholate, deoxycholate, and chenodeoxycholate, but not tauroursodeoxycholate or ursodeoxycholate, increased protoporphyrin metabolism 1.7- to 2.7-fold over control (0 bile acid) values. Bile acid infusion ranging from 0.175 to 1.4 mumol/min confirmed that both taurocholate and chenodeoxycholate increased protoporphyrin disposal significantly more than ursodeoxycholate. For all bile acids, the increase of protoporphyrin metabolism was most pronounced between biliary bile acid excretion rates of 10-50 nmol/min.g liver. These data indicate that (a) bile acids facilitated protoporphyrin metabolism, (b) bile acid structure influenced the effect, and (c) ursodeoxycholate may not be a prime candidate to study the role of bile acids in the treatment of protoporphyria.     

Arachidonate metabolism in D-galactosamine or carbon tetrachloride-induced acute and chronic liver injuries in rats.

Arachidonate metabolism was examined in rats with experimentally induced acute and chronic liver injuries. Acute liver injury was induced by a single administration of D-galactosamine (D-Galn) and lipopolysaccharide (LPS) or carbon tetrachloride (CCl4). Chronic liver injury was produced by several administrations of CCl4 for 5 weeks. Non-parenchymal liver cells from rats with D-Galn/LPS-induced acute liver injury produced prominently leukotriene B4 and 5-hydroxy-arachidonic acid which were hardly synthesized by the normal rat liver. No apparent changes were observed in the arachidonate metabolism of the non-parenchymal cells of the acute CCl4-injured liver. In chronic liver injury, the production of 6-ketoprostaglandin F1 alpha, a stable metabolite of prostaglandin I2, by the non-parenchymal cell fraction was significantly enhanced in contrast with the fixed amount of the other arachidonate metabolites. These results suggested the arachidonate metabolism by non-parenchymal liver cells might change according to the pathogenesis of the liver disease.     

Hepatocyte proliferation and apoptosis in rat liver after liver injury

BACKGROUND/AIMS: In this paper the early phase of proliferate response and apoptosis of hepatocytes after partial liver resection, during reperfusion after ischemia and during sepsis is demonstrated. METHODOLOGY: Experiments were conducted in a rat model with regeneration times of 0.5-24 hours after injury. Proliferation was analyzed by Ki-67 immunohistochemistry and confirmed by double staining with CK18 in FACS. Apoptosis was analyzed by TUNEL technique. RESULTS: Periportal hepatocytes enter the cell cycle already 0.5-2 hours after injury in all three models. This early proliferative response is predominant periportally localized. During reperfusion and during sepsis there was a strict pericentral apoptosis of hepatocytes found. CONCLUSIONS: An early periportal proliferation of hepatocytes is a common reaction of the liver to injury. This proliferation takes place much earlier then the main proliferative response 24-72 h after partial resection. This predominant periportal proliferation together with the pericentral apoptosis fit to the concept of the "streaming liver" in liver regeneration.     

Acute effects of pioglitazone on glucose metabolism in perfused rat liver

Pioglitazone, a thiazolidinedone derivative, decreases insulin resistance and improves hyperglycemia in insulin-resistant obese and/or diabetic animals. However, the mechanisms by which hyperglycemia is improved are not well defined. We investigated the effects of pioglitazone on hepatic glucose metabolism using a perfused rat liver model. Perfusion with the buffer containing 1 – 10 μm pioglitazone for 20 min dose-dependently increased the hepatic fructose 2,6-bisphosphate content, a potent activator of 6-phosphofructo 1-kinase. The furctose 2,6-bisphosphate level after 20 min perfusion with 10 μm pioglitazone was 64.9± 14.5 pmol/mg ⋅ protein, significantly higher than the control (48.3±10.9 pmol/mg ⋅ protein). When the liver from a starved for 48 h rat was perfused with the buffer containing 2 mm lactate but no glucose, glucose was generated from lactate via the gluconeogenic pathway and flowed into the effluent perfusate at a constant rate of 31±0.6 μmol/g ⋅ liver/h. The addition of 10 μm pioglitazone decreased the glucose output rate to 19.3±3.8 μmol/g ⋅ liver/h. Dose-dependent inhibition of glucose output by pioglitazone was observed in the 1 – 10 μm dose range. These results indicate that pioglitazone may not only stimulate glycolysis but also inhibit gluconeogenesis in the liver. These acute and insulin-independent effects on hepatic glucose metabolism may partly account for the diverse anti-diabetic effects of pioglitazone. Received:13 May 1996 / Accepted in revised form: 14 April 1997     

Beneficial effects of fructose-1,6-diphosphate infusion on liver regeneration after ischemic liver injury.

The effect of fructose-1,6-diphosphate (FDP) on cellular viability after partial hepatectomy in partial ischemic liver was investigated in rats. The administration of FDP did not increase blood flow in the hepatic tissue; however, it significantly suppressed the elevation of serum liver functions for 24 hours after partial hepatectomy. Levels of DNA synthesis, protein synthesis, and labeling index were significantly higher in the groups administered divided doses of FDP before and after partial hepatic ischemia than in the control group (P less than 0.01). Thus, these findings indicate that FDP has cytoprotective and hepatotrophic effects on liver with ischemic injury and that divided dose administration of FDP is more effective than bolus doses in decreasing damage following ischemic and reperfusion injury.     

茶多酚对雷公藤内酯醇致小鼠肝损害的保护作用

目的:观察不同剂量雷公藤内酯醇(TPI)致小鼠肝损害的作用以及茶多酚(TP)对其损害的保护作用,并初步探讨相关机制．方法:昆明种小鼠70只,随机平均分成5 组:低剂量TPI(0．015 mg／kg)组(A)、高剂量 TPI(0．03 mg／kg)组(B)、低剂量TPI(0．015 mg／ kg) TP(300 mg／kg)组(C)、高剂量 TPI(0．03 mg／kg) TP(300 mg／kg)组(D)和正常对照组．实验60 d后观察各组小鼠肝功能酶、肝匀浆丙二醛(MDA)含量、过氧化物歧化酶 (SOD)活性、谷胱甘肽-S转移酶(GST)活性及肝肾病理组织学的特点．结果:与对照组相比,A,B组血清ALT、肝匀浆MDA的含量显著提高(ALT:63．7±10．9, 95．8±12．5 μkat／L vs 38．2±5．6 μkat／L,P<0．01; MDA:8．11±1．38,12．86±2．01 nmol/mgp vs 6．39±0．98 nmol／mgp,P<0．05或P<0．01),肝匀浆SOD和GST的活性显著降低(92．31±10．26, 75．93±9．11 U／mgp vs 122．23±15．27 U／mgp, P<0．05或P<0．01;15．17±4．41,11．25±3．46 U／ mgp vs 20．53±5．16 U／mgp,P<0．05或P<0．01), 病理组织学均可见肝肾细胞变性等改变;C,D 组血清ALT(39．4±5．0,43．4±6．3 μkat／L)、肝匀浆MDA含量(6．42±1．04,6．58±1．19 nmol／ mgo)、SOD活性(119．10±12．72,109．53± 11．58 U／mgp)无显著性改变,肝肾病理组织学未见异常．C组肝匀浆GST的活性增高(27．19 ±5．24 U／mgp vs 20．53±5．16 U／mgp,P<0．05)．结论:TPI对小鼠肝肾均有一定的损害,而TP 具有很好的保护作用,其机制与对抗脂质过氧化反应和诱导肝药酶有关．