Impact of endothelin-1 on microcirculatory disturbance after partial hepatectomy under ischemia/reperfusion in thioacetamide-induced cirrhotic rats

BACKGROUND: Endothelin (ET)-1 contributes to hepatic ischemia and reperfusion (HIR) injury in normal liver. This study was conducted to clarify the role of ET-1 in HIR injury in cirrhotic state. MATERIALS AND METHODS: Using thioacetamide-induced cirrhotic rats with spontaneous portosystemic shunt, we determined the changes in plasma aspartate aminotransferase (AST) levels, plasma and hepatic ET-1 values, 7-day survival rates, and hepatic oxygen saturation (SO(2)) by time-resolved spectroscopy as an indicator of hepatic microcirculation under intermittent or continuous total hepatic ischemia with subsequent partial hepatectomy. RESULTS: Hepatic ET-1 levels in cirrhotic rats were significantly higher than those in noncirrhotic rats. Plasma and hepatic ET-1 levels at 1, 3 and 6 h of reperfusion after intermittent hepatic ischemia were significantly lower than those after continuous hepatic ischemia. In cirrhotic animals subjected to intermittent hepatic ischemia, the elevation of plasma AST levels at 1, 3 and 6 h of reperfusion and the decline in hepatic SO(2) at the end of 60-min hepatic ischemia and after reperfusion were significantly suppressed when compared with those subjected to continuous hepatic ischemia. Pretreatment with a nonselective endothelin receptor antagonist in continuous hepatic ischemia significantly ameliorated plasma AST levels and hepatic SO(2) values with less hepatic sinusoidal congestion, resulting in an improvement in the 7-day survival rate. CONCLUSIONS: Continuous hepatic ischemia in the cirrhotic liver has disadvantages relating to microcirculatory derangement with more ET-1 production in partial hepatectomy. In liver surgery, pharmacological regulation of ET-1 production may lead to attenuation of reperfusion injuries for ischemically damaged cirrhotic liver.     

Effect of intravenous prostaglandin E1 on pial vessel diameters and intracranial pressure in rabbits

BACKGROUND: The main advantages of prostaglandin E1 (PGE1) for induced hypotension during neurosurgery include a rapid onset of action, a quick recovery from hypotension, lack of toxicity, maintenance of adequate perfusion to vital organs, and maintenance of cerebral blood flow reactivity to carbon dioxide during hypotension. However, there is no report that shows the effect of PGE1 on cerebral microvessel diameter and only a few data are available that show the effect of PGE1 on intracranial pressure. The aim of this study was to measure cerebral arteriole and venule diameters and intracranial pressure (ICP) during PGE1-induced hypotension to evaluate whether PGE1 is suitable for neuroanesthesia. METHODS: We measured the effects of 0.1, 0.3, 1.0, 3.0, and 10.0 microg x kg(-1) x min(-1) of intravenous PGE1 on mean arterial pressure (MAP), cerebral arteriole and venule diameters and ICP in anesthetized rabbits. RESULTS: MAP decreased statistically significantly from baseline at the infusion rates of 1.0, 3.0, and 10.0 microg x kg(-1) x ml(-1). Arteriole diameter increased significantly from the baseline at the infusion rate of 10.0 microg x kg(-1) x ml(-1) (18% from control). Venule diameter did not change from baseline value at any infusion rate. ICP did not change from baseline value at any infusion rate. CONCLUSION: We conclude that PGE1 might be a suitable drug for induced hypotension in neurosurgery from the viewpoint of its small effect on the cerebral microvessels and ICP.     

The effects of intraportal prostaglandin E1 administration on hepatic warm ischemia and reperfusion injury in dogs

To determine the route of prostaglandin E₁ (PGE₁) administration which would have the greatest protective effect against hepatic warm ischemia, two experiments were performed using dogs. The pharmacokinetics of PGE₁ were investigated in a preliminary study, after which, the effects of PGE₁ in a 90-min warm ischemic liver model were examined. The dogs were divided into three groups of ten, according to the treatment given: group A was an untreated control group, group B received PGE₁ intravenously, and group C received PGE₁ intraportally. The PGE₁ was infused continuously at a rate of 0.02 g/kg/min before and after ischemia. All the dogs in groups A and B died within 24 h of induced ischemia. Whereas, six of the ten dogs in group C survived for over 3 days. The arterial ketone body ratio was not maintained in groups A and B, but it was in group C. Furthermore, in group C the serum lipid peroxide level, which reflects hepatocellular membrane damage, was maintained at a lower level than that in the other groups after ischemia. Electron microscopy revealed sinusoid destruction and changes in both the plasma membrane and parenchymal cell mitochondria in groups A and B, while in group C these structures were well preserved. These findings confirmed that intraportally administered PGE₁ improved the hepatic microcirculation and stabilized the hepatocellular membranes. Our results indicate that intraportal administration of PGE₁ has a greater protective effect than intravenous administration against warm ischemic liver injury.     

血红素加氧酶-1诱导对鼠肝缺血再灌注损伤的保护作用

目的研究血红素加氧酶-1(heme oxygenase-1,HO-1)在鼠肝缺血再灌注损伤肝组织中的表达及其作用。方法建立小鼠部分肝脏热缺血再灌注损伤模型,36只清洁级Balb/C小鼠随机分为3组: 假手术组(S组)、缺血/再灌注损伤组(I/R组)、HO-1诱导剂氯化高铁血红素(hemin)预处理组(HM组)。免疫组化半定量分析肝组织HO-1蛋白的表达,检测血清AST和ALT,肝组织丙二醛(MDA)含量及超氧化物歧化酶(SOD)活性,并观察肝组织的病理变化。结果与S组比较,I/R组HO-1蛋白表达显著增强,hemin预处理后,HO-1蛋白表达较I/R组增高(P<0．01)。I/R组AST,ALT活性和MDA的含量显著高于S组,而HM组均显著低于I/R组(P<0．01);I/R组SOD活性下降,而HM组显著高于I/R组(P<0．01)。HM组病理损伤程度明显轻于I/R组。结论 HO-1在鼠肝缺血再灌注损伤肝组织中表达上调,对肝脏具有保护效应。     

丙氨酰-谷氨酰胺二肽保护大鼠肝脏缺血再灌注损伤的实验研究

目的探讨丙氨酰-谷氨酰胺二肽(Ala-Gln)对肝脏缺血再灌注损伤(HIRI)的保护作用.方法采用大鼠HIRI模型(Pringle's法阻断入肝血流30 min),分谷氨酰胺组(G组)及对照组(C组),检测再灌注后血清肝生化酶、肝组织还原型谷胱甘肽(GSH)及超氧化物歧化酶(SOD)水平,对肝组织进行光镜与电镜检查,并计算术后24 h生存率.结果再灌注1h,G组血清ALT(499.25±120.84)U/L、LDH(6 956.00±2 443.93)U/L的水平均显著低于C组(ALT823.56±328.71,P<0.05;LDH11 715.31±2 993.50,P<0.01);再灌注24 h,两组血清ALT、LDH的水平均有显著恢复,但G组(ALT176.69±151.84;LDH415.38±213.68)水平仍显著低于C组(ALT548.25±257.25;LDH1 958.50±687.32;P<0.01).再灌注1 h及24 h,G组GSH的水平分别为(1 216.09±152.78)μg·g-1·p、(899.73±57.75)μg·g-1·p,均明显高于C组(分别为856.68±117.64,P<0.01;800.50±94.79,P<0.05);两组SOD的活性无统计学差异.G组肝脏组织学与细胞学损害均明显轻于C组.G组术后24h生存率为78.57%(11/14),明显高于C组的45.45%(10/22)(P<0.05).结论 Ala-Gln(Gln)对HIRI具有保护作用,而这种保护作用部分是通过维持肝脏组织中GSH的含量来介导的.     

Post-ischemic intraportal adenosine administration protects against reperfusion injury of canine liver

Although adenosine has been postulated to inhibit ischemia-reperfusion injury in various tissues, its in vivo cytoprotective mechanism is not fully known. The aim of this study was to determine the effect of intraportally infused adenosine on reperfusion injury in the canine liver. Two h ischemia and reperfusion of the liver were induced in beagle dogs by clamping the portal triad. Either adenosine or saline was infused in the portal vein after reperfusion for 60 min. Levels of serum aspartate aminotransferase and alanine aminotransferase and the survival of animals were examined. Hepatic levels of protein carbonyls and glutathione were also measured, as markers of oxidative stress. One h after reperfusion, the liver was perfused with nitroblue tetrazolium and the formation of formazan was observed to evaluate superoxide formation. Twenty-four h after reperfusion, 100% of animals in the adenosine group and 33% of animals in the control group survived. Adenosine significantly decreased the reperfusion-induced increase in serum levels of aspartate aminotransferase and alanine aminotransferase. Adenosine also suppressed the formation of protein carbonyls and the decrease in glutathione levels. Histologically, neutrophil infiltration, superoxide formation, and apoptosis were decreased by adenosine. These results suggest that intraportally infused adenosine attenuates reperfusion injury of the liver, presumably by suppressing the activation of neutrophils and oxidative stress. Received for publication on Oct. 15, 1999; accepted on Nov. 11, 1999     

Beneficial effects of administering intraportal prostaglandin E1 postoperatively to hepatectomy patients with massive intraoperative blood loss

Massive intraoperative blood loss is a major cause of complications following hepatectomy. To evaluate the efficacy of intraportal prostaglandin E₁ (PGE₁) for preventing liver deterioration in hepatectomy patients with an intraoperative blood loss of over 2000 ml, a retrospective analysis was conducted on 10 patients given intraportal PGE₁ (portal group), 6 given intravenous PGE₁ (venous group), and 10 given no treatment (control group). PGE₁ was infused at 250 or 500 g/day in the portal group and at 720 g/day in the venous group, and continued for 3 days postoperatively. Alanine aminotransferase (ALT) and total bilirubin (T.Bil) were measured on postoperative days (PODs) 1, 3, 5, and 7. ALT was lower in the portal group than in the other two groups on each POD, and significantly lower than in the control group on POD 3 (P<0.05). T.Bil was significantly lower in the portal group than in the control group on PODs 5 and 7 (P<0.05). T.Bil on POD 7 was under 1.5 mg/dl in 1 (10.0%), 6 (60.0%), and 2 (33.3%) of the control, portal, and venous group patients, respectively, with a significant difference between the control and portal groups (P<0.05). These results confirmed that intraportal PGE₁ was beneficial for improving hepatic function and preventing cholestasis in patients with a blood loss of over 2000 ml at risk of developing postoperative liver deterioration.     

Experimental evaluation of the effects of the intraportal administration of cyclic guanosine monophosphate on ischemia/reperfusion in the porcine liver

This study was done to examine the protective effects of cyclic guanosine monophosphate (cGMP), a second messenger of nitric oxide, for ischemia/reperfusion injury of the liver, since it is known to induce vasodilatation and to inhibit platelet aggregation. Using an experimental model of porcine liver ischemia, 8-bromoguanosine 3′,5′ monophosphate, a cGMP analog, was continuously administered into the portal vein before ischemia and after reperfusion 30 min for each in the cGMP group (n=6). Saline water was administered in the same way in the control group (n=6). The cardiac output (CO), mean arterial blood pressure (MAP), portal venous flow (PVF), hepatic arterial flow (HAF), hepatic tissue blood flow (HTBF), and hepatic tissue cGMP level were determined. Hepatic enzymes and the bile discharge were also assessed as indicators of hepatic function. The hepatic tissue cGMP level was significantly higher, and PVF, HTBF, and the bile discharge were significantly greater in the cGMP group, while there were no remarkable differences between the groups with CO, MAP, HAF, and hepatic enzymes. In conclusion, the continuous supplementation of cGMP into the portal vein was found to be beneficial for preserving both the hepatic circulation and, consequently, the hepatic function of after warm ischemia of porcine liver.     

Role of leukotrienes on hepatic ischemia/reperfusion injury in rats

BACKGROUND: Leukotrienes (LT), composed of cysteinyl LT (cLT; LTC(4), LTD(4), and LTE(4)) and LTB(4), are potent lipid mediators enhancing the vascular permeability and recruitment of neutrophils, which are common features of hepatic ischemia/reperfusion (I/R) injury. The aim of this study was to investigate whether LT can mediate the liver and lung injuries following hepatic I/R. MATERIALS AND METHODS: Sprague-Dawley rats were subjected to 90 min of partial hepatic ischemia followed by 3, 12, and 24 h of reperfusion. In the hepatic and pulmonary tissues, LT content and the mRNA expression of LT-synthesis enzymes, 5-lypoxygenase (5-LO), LTC(4) synthase (LTC(4)-S), and LTA(4) hydrolase (LTA(4)-H) were measured. Tissue injuries were assessed by plasma ALT, histological examination, and wet-to-dry tissue weight ratios. RESULTS: The cLT content in the hepatic tissue after 12 and 24 h reperfusion was increased 4- to 5-fold compared to controls and this was accompanied by the enhancement of hepatic edema and plasma ALT elevation. There were no significant changes in the mRNA expression of LT-synthesis enzymes in both tissues. LTB(4) levels were not increased despite a significant neutrophil infiltration in both tissues. CONCLUSIONS: These data suggest that cLT are generated in the liver during the reperfusion period and may contribute to the development of hepatic edema and exert cytotoxicity. Factors other than LTB(4) may contribute to neutrophil infiltration.     

Increased intraabdominal pressure impairs liver regeneration after partial hepatectomy in rats

BACKGROUND: There are many experimental studies showing that increased intraabdominal pressure (IAP) reduces liver blood flow, leading to ischemia and portal venous congestion. But, there is no study evaluating the effect of increased IAP on liver regeneration. It is well known that acute liver ischemia and portal venous congestion impair liver regeneration. We, therefore, aimed to determine the effect of increased IAP on liver regeneration in this study. METHODS: Sprague-Dawley rats underwent partial hepatectomy with or without IAP of 12-14 mm Hg for 24 h or sham operation. Rats were randomly divided into six groups: two sham-operated groups, two hepatectomy groups, and two hepatectomy with increased IAP groups. Mitotic index, proliferating cell nuclear antigen (PCNA)-labeling index, and liver regeneration rate as liver regeneration parameters were studied on day 1 or on day 4 after operation. Additionally, serum aspartate transaminase (AST) level and histopathological changes in intestinal mucosa were studied. RESULTS: Hepatectomy with/without increased IAP groups had significantly higher serum AST levels than the sham-operated group on day 1. Serum AST level was found to be significantly higher in the hepatectomy with increased IAP group than in the other groups on day 4. Intestinal mucosal injury was found in the hepatectomy with increased IAP groups on days 1 and 4. Mitotic index and PCNA-labeling index were markedly higher in all hepatectomy with/without increased IAP groups than in the sham-operated groups. However, together with liver regeneration rate, both indices were significantly less in the hepatectomy with increased IAP groups than in the hepatectomy groups both on day 1 and on day 4. CONCLUSION: Maintenance of IAP between 12 and 14 mm Hg for 24 h impaired liver regeneration after partial hepatectomy in rats.     

前列地尔在肝移植中使用的临床意义评价

目的　了解前列地尔 (前列腺素E1的微脂球载体制剂 ,LipoPGE1)对肝移植受体术后血小板聚集功能、肝血供、肝功能及凝血功能、血栓形成的影响 ,以评价前列地尔使用于临床肝移植的意义。方法　以肝移植术后使用前列地尔 (10 μgivq12h ,连续 7d)的 4 0例为治疗组 ,于术前、术后7、10d分别检测其血小板聚集功能、凝血功能、肝功能 ,同时以彩色多普勒超声检测受体肝动脉、门静脉血流峰值 ,比较术前术后上述各指标的变化 ;同时以 36例未使用前列地尔的肝移植受体为历史病例对照组 ,比较两组术后肝血管血栓形成的差异。结果　前列地尔虽然对肝移植术后血小板聚集功能的抑制统计学意义不显著 ,但在治疗组 ,使用前列地尔 7d后 ,移植肝的动脉血供较术前显著增加 ,并且在停药 3d后仍维持于高于术前的水平 ,对早期肝功能的恢复、凝血功能的改善有明显的促进作用 ;对预防术后肝血管尤其是肝动脉血栓形成有一定帮助。结论　前列地尔在肝移植术后使用对早期肝动脉的血供增加有显著的促进作用 ,有利于移植肝的存活和功能恢复。     

Effects of exogenous prostaglandin E1 in hepatectomized patients

The efficacy of prostaglandin E1 (PGE1) in preventing hepatic failure after hepatectomy was investigated prospectively in eight PGE1-treated patients and in seven untreated controls. The patients in the PGE1-treated group received PGE1 (0.03 μg/kg per min) intravenously for 72 h beginning at the initiation of surgery. The cardiac index increased markedly and the systemic vascular resistance decreased markedly during PGE1 treatment, while no significant changes were observed in the control group. The platelet count in the PGE1-treated group decreased slightly, while that in the control group decreased significantly during the first 3 postoperative days. The percent change of alanine aminotranferase in the PGE1-treated group was less than that in the control group. These findings suggest that the administration of exogenous PGE1 following hepatectomy increases hepatic blood flow and suppresses platelet aggregation, and therefore may be cytoprotective to the remnant liver. Thus, PGE1 may be effective in preventing hepatic failure after hepatectomy.     

Ozone oxidative preconditioning is mediated by A1 adenosine receptors in a rat model of liver ischemia/ reperfusion

The liver is damaged by sustained ischemia in liver transplantation, and the reperfusion after ischemia results in further functional impairment. Ozone oxidative preconditioning (OzoneOP) protected the liver against ischemia/reperfusion (I/R) injury. The aim of this study was to investigate the role of A₁ adenosine receptor on the protective actions conferred by OzoneOP in hepatic I/R. By using a specific agonist and antagonist of the A₁ subtype receptor (2-chloro N6 cyclopentyladenosine, CCPA and 8-cyclopentyl-1,3-dipropylxanthine, DPCPX respectively), we studied the role of A₁ receptor in the protective effects of OzoneOP on the liver damage, nitiric oxide (NO) generation, adenosine deaminase activity and preservation of the cellular redox balance. Immunohistochemical analysis of nuclear factor-kappa B (NF-κB), tumor necrosis factor alpha (TNF-α) and heat shock protein-70 (HSP-70) was performed. OzoneOP prevented and/or ameliorated ischemic damage. CCPA showed a similar effect to OzoneOP + I/R group. A₁AR antagonist DPCPX blocked the protective effect of OzoneOP. OzoneOP largely reduced the intensity of the p65 expression, diminished TNF-α production, and promoted a reduction in HSP-70 immunoreactivity. In summary, OzoneOP exerted protective effects against liver I/R injury through activation of A₁ adenosine receptors (A₁AR). Adenosine and ^.NO produced by OzoneOP may play a role in the pathways of cellular signalling which promote preservation of the cellular redox balance, mitochondrial function, glutathione pools as well as the regulation of NF-κB and HSP-70.     

Kupffer细胞在肝移植缺血再灌注损伤中的双重作用

Kupffer细胞足定居于肝内的巨细胞,在月十移植缺血再灌注损伤中发挥着重要的作用,门静脉恢复血流后刺激Kupffer细胞激活,释放活性氧族、多种炎性介质和细胞因子,对肝脏造成损伤.另一方面又可上调HO-1的表达,保护肝脏缺血再灌注损伤,因此,Kupffer细胞在肝移植缺血再灌注损伤中发挥着双重效应.     

Efficacy of prostaglandin I2 analog on liver grafts subjected to 30 minutes of warm ischemia

Due to the fact that no effective conditioning agent for hemodynamically unstable donors exists, the number of suitable donors is limited. The efficacy of OP-41483, a stable analog of prostaglandin I₂, as a conditioning agent of the liver was investigated in this study using pigs. OP-41483 was administered via the portal tributary for 10 min before 30 min of warm ischemia. Graft livers were procured after perfusion with OP-41483 in cold normal saline, the flushed with OP-41483 in Euro-Collins solution and placed in cold storage prior to orthotopic transplantation. OP-41483 was also administered intraportally for 120 min after reperfusion. Biochemical and histological studies, and survival rates were compared with a control group not given OP-41483 in an otherwise similar experimental protocol. The graft function recovered better in the OP group than in the control group, shown by the lactate values and lactate-to-pyruvate ratios. The marked congestion noted in the parenchyma of the control group livers was minimal in the OP group, verifying the microcirculatory effect of prostaglandin I₂ by its vasodilatory and antithrombotic actions. These findings suggest that OP-41483 has some protective effect as a conditioning agent in liver transplantation, with timing of administration being crucial.     

Effect of prostaglandin E1 on arterial ketone body ratio in hepatectomy

We evaluated the effect of prostaglandin E₁ (PGE₁) administration during hepatectomy on arterial ketone body ratio (AKBR), which is an indicator of liver function, and on other liver functions in the postoperative period. Eighteen patients were divided into two groups: Continuous intravenous administration of PGE₁ (0.02 μg·kg⁻¹·h⁻¹) was started immediately before hepatic resection and ceased at the end of operation in nine patients (PGE₁ group); the other nine did not receive PGE₁ (control group). After hepatic resection, a significant increase in AKBR was observed in the PGE₁ group. However, no change was observed in the control group. In the PGE₁ group, total bilirubin and SGOT recovered more rapidly to the preoperative level than in the control group. These findings suggested that PGE₁ might have a protective effect on the liver.     

A pharmacological analysis of prostaglandin E1 on portal blood flow after partial hepatectomy in rats

Portal venous flow (PVF) and portal venous pressure (PVP) were examined after the jugular or portal injection of Prostaglandin E₁ (PGE) in rats partially hepatectomized by either 40% or 66%. In the 66% hepatectomized animals, the jugular injection of PGE at 5.0 g/kg/min produced an increase in PVF concomitant with a fall in systemic arterial pressure (SAP), while PVP remained unchanged. The portal injection of PGE at 0.5 g/kg/min increased PVF to a level equivalent to that evoked by the jugular injection of 5.0 g/kg/min PGE, without any change in SAP. PVP was reduced synchronistically with an increase in PVF. The PVF response to a portal injection of PGE at 0.5 g/kg/min was not reproduced in liver intact rats. These results suggest that PGE is potent in increasing PVF in the partially resected condition of the liver and that the portal vascular bed is involved in this response.     

血管紧张素转换酶在大鼠原位肝移植缺血再灌注损伤中的作用

目的 通过研究血管紧张素转换酶(ACE)在大鼠原住肝移植(OLT)中的表达情况及其与OLT后缺血再灌注损伤(IRI)的相关性,初步探讨肾素-血管紧张素系统在肝移植缺血再灌注损伤中的可能作用.方法 将OLT大鼠分为无冷保存组(NCP)及冷保存组(CP),假手术组作对照,组织学检查及血ALT检测观察缺血再灌注损伤程度,Real-time PCR,Western blot和免疫组化分别检测ACE的mRNA,蛋白表达及其组织定位,以上指标同时在术后多个时间点作动态观察.结果 OLT后,肝组织ACE在mRNA及蛋白水平均显著高于对照组(P<0.05,P<0.01),且CP组明显高于NCP组(P<0.05);CP组血清ALT水平显著高于NCP组,组织损伤更明显;动态观察显示ACE水平与血清ALT水平及组织损伤程度有很好的相关性.结论 ACE与冷保存导致的OLT后IRI的炎症损伤密切相关,肾素-血管紧张素系统可能在OLT后的IRI中有重要作用.     

Pharmacologic preconditioning effects: Prostaglandin E1 induces heat-shock proteins immediately after ischemia/reperfusion of the mouse liver

Prostaglandin E1 (PGE1) has several potential therapeutic effects, including cytoprotection, vasodilation, and inhibition of platelet aggregation. This study investigates the protective action of PGE1 against hepatic ischemia/reperfusion injury in vivo using a complementary DNA microarray. PGE1 or saline was continuously administered intravenously to mice in which the left lobe of the liver was made ischemic for 30 minutes and then reperfused. Livers were harvested 0, 10, and 30 minutes postreperfusion. Messenger RNA was extracted, and the samples were labeled with two different fluorescent dyes and hybridized to the RIKEN set of 18,816 full-length enriched mouse complementary DNA microarrays. Serum alanine aminotransferase and aspartate aminotransferase levels at 180 minutes postreperfusion were significantly lower in the PGE1-treated group than in the saline-treated group. The cDNA microarray analysis revealed that the genes encoding heat-shock protein (HSP) 70, glucose-regulated protein 78, HSP86, and glutathione S-transferase were upregulated at the end of the ischemic period (0 minutes postreperfusion) in the PGE1 group. Our results suggested that PGE1 induces HSPs immediately after ischemia reperfusion. HSPs might therefore play an important role in the protective effects of PGE1 against ischemia/reperfusion injury of the liver.