Systemic hypotension and pressor responsiveness in cholestasis. A study in conscious 3-day bile duct ligated rats

It has been postulated that the physiological basis for systemic hypotension in cholestatic liver disease is the attenuated responsiveness of the cardiovascular system to sympathetic stimulation. Using conscious 3-day bile duct ligated rats, we tested this hypothesis by measuring the vasopressor and vasodilator responses following intravenous infusions of norepinephrine, tyramine, angiotensin II, angiotensin I and isoproterenol, in conjunction with the pressor responses to a head-up vertical tilt and a controlled hemorrhage. The results were compared to those obtained in conscious sham-operated rats. Bile duct ligation reduced the mean arterial blood pressure without a significant increase in heart rate. The pressor responses to the aforementioned drugs obtained in the bile-duct ligated rats were significantly attenuated from those the sham-operated rats. In contrast, bile duct ligation had no effect on the pressor responses to tilting and hemorrhage when compared to the responses obtained in the sham-operated rats. Despite the presence of systemic hypotension and attenuation of pressor response to vasoactive drugs, the ability of the cardiovascular system to respond to physiological stimuli appears to be intact in this model. Therefore, we conclude that blunted pressor responsiveness of the cardiovascular system is probably not an important physiological determinant of systemic hypotension in cholestatic liver disease.     

Effect of propranolol on hepatic and systemic hemodynamics in dogs with chronic bile duct ligation

Propranolol has been reported to reduce portal and wedged hepatic vein pressures in man and may be useful for the prevention of variceal bleeding. However, its mechanism of action remains unclear. We have examined the effect of propranolol on the systemic and hepatic circulations in dogs with chronic bile duct ligation and secondary biliary cirrhosis. Under anesthesia, eight dogs received four increasing doses of propranolol as an i.v. bolus followed by continuous infusion. Systemic and hepatic hemodynamic parameters were measured in basal conditions and after a 30 min infusion for each dose. Portal vein and hepatic artery blood flows were measured with electromagnetic flow meters. All dogs had portal hypertension (portal venous pressure 15.3 +/- 0.8 mm Hg), a hyperdynamic circulation and severe liver disease resulting in a marked decrease of propranolol systemic clearance (8.75 ml per min per kg) and extraction (40%). The first dose of propranolol induced a decrease in heart rate (-27%) and in cardiac index (-21%), and an increase in systemic vascular resistance (+20%). With increasing doses, the systemic vascular resistance decreased with an increase in the cardiac index. Propranolol was not associated with significant modifications of hepatic hemodynamics: portal, wedged and free hepatic venous pressures and hepatic artery blood flow were stable, and portal blood flow decreased slightly at very high propranolol levels. In seven dogs studied without dissection of the hepatic vessels, there was a small decrease in portal pressure, but not in wedged and free hepatic venous pressures with increasing doses of propranolol. Thus, in dogs with intrahepatic portal hypertension, propranolol has significant effects on systemic hemodynamics, but only minimal effects on the hepatic circulation.     

Response of renal nerve activity to high NaCl food intake in dogs with chronic bile duct ligation

Hepatic sensory systems are thought to play an important role in the response of renal nerve activity and natriuresis to oral NaCl load. In this study, responses of renal nerve activity and urinary Na⁺ and Cl^- excretions to a high-NaCl food intake (20 g/kg boiled rice containing 0.4 g/kg NaCl) were examined in sham-operated dogs (n = 12) and dogs with chronic bile duct ligation (CBDL; n = 10). In sham-operated dogs, renal nerve activity gradually decreased and reached minimal value (50% +/- 7% of the control value) at 100 minutes after the high-NaCl food intake and remained depressed until 4 hours after the food intake. Of the orally administered sodium and chloride, 27% +/- 5% and 23% +/- 6% were excreted over the following 4 hours, respectively. In CBDL dogs, the decrease in renal nerve activity induced by the high-NaCl food was completely abolished and only 4% +/- 1% of the loaded Na+ and 3% +/- 2% of the loaded Cl^- were excreted. Furthermore, liver tissue norepinephrine concentration in CBDL dogs decreased to 21% of that of sham-operated dogs. These results suggest that (1) In CBDL dogs, the decrease in renal nerve activity induced by a high-NaCl food is completely abolished, probably because of the impairment of hepatic neural regulation. (2) The lack of renal nerve response may contribute, at least in part, to the abnormalities in body fluid homeostasis in cirrhosis. (Hepatology 1996 Feb;23(2):303-9)     

Intrapulmonary vascular dilatation and nitric oxide in hypoxemic rats with chronic bile duct ligation

BACKGROUND/AIMS: Nitric oxide (NO) has been suggested as the major cause of pulmonary vascular dilatation and hypoxemia in hepatopulmonary syndrome (HPS). The aim of this study was to assess the effect of NO on arterial oxygenation in rats with common bile duct ligation (CBDL rats), a model of HPS. METHODS: Arterial blood gases were measured in 44 CBDL rats and 44 Sham rats under unrestrained conditions. Intrapulmonary shunting was assessed with (141)Ce-labeled microspheres (15-mum diameter) and serum nitrate/nitrite levels were measured by HPLC. The effect of NOS inhibition on A-aDO(2) was studied using L-NAME. RESULTS: A decrease of PaO(2) below 82.7 mmHg (the mean value-2sigma in Sham rats) was seen in 43% of CBDL rats. Intrapulmonary shunting was greater in CBDL rats than in Sham rats (P<0.001). A correlation between the extent of shunting and A-aDO(2) was found in all animals studied (r=0.89, P<0.001, n=16). Serum levels of nitrate/nitrite increased significantly across the lungs, and the increase was significantly correlated with A-aDO(2) in the total population of animals studied. Administration of L-NAME to CBDL rats achieved a significant improvement of A-aDO(2). CONCLUSIONS: These results suggest that pulmonary vascular dilatation due to NO leads to hypoxemia in CBDL rats.     

Yes-associated protein regulates the hepatic response after bile duct ligation

Human chronic cholestatic liver diseases are characterized by cholangiocyte proliferation, hepatocyte injury, and fibrosis. Yes-associated protein (YAP), the effector of the Hippo tumor-suppressor pathway, has been shown to play a critical role in promoting cholangiocyte and hepatocyte proliferation and survival during embryonic liver development and hepatocellular carcinogenesis. Therefore, the aim of this study was to examine whether YAP participates in the regenerative response after cholestatic injury. First, we examined human liver tissue from patients with chronic cholestasis. We found more-active nuclear YAP in the bile ductular reactions of primary sclerosing cholangitis and primary biliary cirrhosis patient liver samples. Next, we used the murine bile duct ligation (BDL) model to induce cholestatic liver injury. We found significant changes in YAP activity after BDL in wild-type mice. The function of YAP in the hepatic response after BDL was further evaluated with liver-specific Yap conditional deletion in mice. Ablating Yap in the mouse liver not only compromised bile duct proliferation, but also enhanced hepatocyte necrosis and suppressed hepatocyte proliferation after BDL. Furthermore, primary hepatocytes and cholangiocytes isolated from Yap-deficient livers showed reduced proliferation in response to epidermal growth factor in vitro. Finally, we demonstrated that YAP likely mediates its biological effects through the modulation of Survivin expression. Conclusion: Our data suggest that YAP promotes cholangiocyte and hepatocyte proliferation and prevents parenchymal damage after cholestatic injury in mice and thus may mediate the response to cholestasis-induced human liver disease. (HEPATOLOGY 2012;56:1097-1107).     

Effect of chronic methylene blue administration on hypoxemia in rats with common bile duct ligation

Aim: Acute administration of methylene blue (MB) can reverse hypoxemia in patients with hepatopulmonary syndrome (HPS). We evaluated the effect of chronic MB administration in common bile duct‐ligated rats, which develop HPS by 5 weeks after surgery. Methods: A total of 96 Sprague–Dawley rats were used, including 63 rats with common bile duct ligation (CBDL), 22 sham‐operated rats and 11 normal control rats. MB (6 mg/kg) was injected s.c. once a day for 4 weeks. Evaluation of hemodynamics and intrapulmonary vascular dilatation (IPVD), as well as blood sampling for arterial blood gas analysis, were done under conscious and unrestrained conditions. Hemodynamics were assessed by the reference sample method using ¹⁴¹Ce‐microspheres (15 µm in diameter), and IPVD was also determined by i.v. injection of these microspheres. Histological examination of the lungs was done with hematoxylin–eosin staining and immunohistochemical staining for von Willebrand factor or vascular endothelial growth factor. Results: Both the arterial oxygen tension and alveolar–arterial oxygen difference were significantly improved in MB‐treated CBDL rats. The hyperdynamic circulation and splanchnic hyperemia seen in untreated CBDL rats were also alleviated by MB treatment. However, IPVD was not affected by MB. Histological examination of the lungs indicated that MB treatment reduced the proliferation of alveolar capillary vessels and angiogenesis, leading to improvement of arterial dysoxygenation. Hepatic synthetic and detoxification functions, as well as renal function, were not altered by MB treatment. Conclusion: Methylene blue may be a candidate treatment for HPS that does not cause deterioration of hepatic or renal function.     

Modification of the cerebrovascular response to noradrenaline by bile duct ligation.

The effects of intracarotid infusions of noradrenaline on the cerebral vasculature were studied in seven baboons with bile duct ligation. Infusion of 8 mug and 16 mug/min of noradrenaline resulted in a significant decrease in cerebral blood flow in the jaundiced animals. In normal baboons, these doses produced cerebrovascular dilatation. These results indicate that there is an increased cerebrovascular sensitivity to noradrenaline in the obstructive jaundice which follows bile duct ligation. It is postulated that noradrenaline smooth muscle uptake mechanisms are disturbed allowing a greater concentration of the amine at the receptor sites.     

Relationships between NOS2 and HO-1 in liver of rats with chronic bile duct ligation.

An increased expression and activity of the heme oxygenase-1 (HO-1) in the liver has been observed in models of hepatic damage. Nitric oxide (NO) seems to be involved in HO-1 regulation. The aim of this work is to assess HO-1 induction and heme oxygenase (HO) activity in rats with bile duct ligation (BDL). We have assessed the effect of chronic inhibition of the NO synthesis by N(G)-nitro-l-arginine methyl ester (l-NAME) on HO-1 induction and HO activity. In the BDL animals, compared with sham-operated ones, we found an increased plasma nitrite and bilirubin concentration, and a marked liver expression of inducible nitric oxide synthase and HO-1, assessed by both Western blot and immunohistochemistry. Chronic l-NAME treatment prevented plasma nitrite increase in animals subjected to BDL. BDL animals treated with l-NAME, compared with untreated BDL rats, showed an important decrease in HO-1 expression and in HO activity (assessed as a decreased plasma bilirubin and bilirubin excretion). In conclusion, our experiments show parallel changes in expression and activity of HO-1 and NOS2 activity in the BDL model of liver damage and suggest that increased NO production is involved in HO-1 overexpression.     

Adaptative bile duct proliferative response in experimental bile duct ischemia

BACKGROUND/AIMS: A rat model of bile duct ischemia was established and used to examine the potential of bile duct proliferation to provide an adaptative response in cholestatic disorders. METHODS: Rats underwent partial or complete arterial deprivation of the liver. Serum biochemical tests, histological analyses and bile secretion measurements were performed at different time points up to 6 weeks after surgery. RESULTS: Rats developed biochemical signs of cholestasis exclusively after complete arterial deprivation. Within 4h, cholangiocytes in these rats showed morphological signs of cell damage. After 48h, they displayed VEGF expression and became proliferative. The proportion of Ki67-labeled cholangiocytes ( approximately 30%) was similar in interlobular bile ducts and periportal ductules. A ductular reaction made of well-formed bile ducts confined to portal tracts developed within 1 week. Bile flow which was initially decreased, was restored at 3 weeks, while the biochemical signs of cholestasis completely resolved at 6 weeks. At this time, the number of bile duct sections was maximal. Fibrosis intensity was also maximal, although moderate (相似文献   

Anesthesia and pressor responsiveness in chronic bile-duct-ligated dogs

Cardiovascular homeostasis is comprised under general anesthesia and in jaundice. Because surgery is often performed on jaundiced patients, it is not altogether surprising that the incidence of perioperative complications is higher in such patients than in nonjaundiced ones. In this study we assessed the potential synergistic effects of anesthesia and jaundice on cardiovascular responsiveness of chronic bile-duct-ligated dogs. Responsiveness to norepinephrine, angiotensin II and isoproterenol was determined before and after chronic bile-duct ligation or sham-operation while the dogs were conscious or under halothane, fentanyl or pentobarbital-sodium anesthesia. These data have shown that halothane- and barbiturate-induced anesthesia do not alter mean arterial blood pressure in unoperated dogs when compared with conscious dogs before laparotomy. Furthermore, these two agents did not modify the pressor, dilator and positive inotropic responses to intravenous infusions of norepinephrine, angiotensin II and isoproterenol. Fentanol, however, reduced mean arterial blood pressure and heart rate without influencing responsiveness to the three vasoactive agents. Blunted responsiveness in the chronic bile-duct-ligated dogs to the three vasoactive agents was observed without any marked changes in mean arterial blood pressure or heart rate. The same blunted responses observed in the conscious, chronic bile-duct-ligated dogs were also seen in the anesthetized, chronic bile-duct-ligated dogs. Halothane caused a marked hypotensive effect in the chronic bile-duct-ligated dogs that was not seen in the sham-operated dogs. Conscious and anesthetized sham-operated dogs responded in the same manner as the conscious and anesthetized dogs before ligation. (ABSTRACT TRUNCATED AT 250 WORDS)     

Alterations in bile ducts and peribiliary microcirculation in rats after common bile duct ligation

The chronological changes in ductular epithelium and peribiliary capiliary plexuses (PBPs) after bile duct ligation are not well understood. Therefore, we examined alterations in both intrahepatic bile ductules and peribiliary microcirculation in rats after ligation of the common bile duct using immunohistochemistry, transmission electron microscopes (TEM), and scanning electron microscopes (SEM). Ductular proliferations appeared first in the peripheral areas of the portal spaces and then gradually advanced along with increasing jaundice. Distorted configuration of the hepatic parenchyma with interconnecting stroma rich in irregular ductules developed 4 weeks after the ligation. Numerous biliary cell types and cells of types intermediate between hepatocytes and biliary cells together with poorly fenestrated capillary-type vessels appeared in the periportal parenchyma, in association with an increased number of canalicular-ductular junctions on TEM. These biliary cells were often found within the lobules and apart from the stroma. SEM examination of hepatic microvascular casts using methacrylated resin showed formation of irregular portal and periportal capillary networks, partly derived from coarsened sinusoids. Direct connections between the newly formed capillary networks and the pre-existing PBPs or sinusoids were numerous, although there were few direct connections between the capillary networks and the hepatic arterial branches. Thus, these proliferated ductules and newly formed complicated capillary networks might play an important role in the effective transport of biliary materials between hepatocytes and native bile ducts or proliferated ductules through the altered microcirculation after bile duct ligation.     

Melatonin prevents increased asymmetric dimethylarginine in young rats with bile duct ligation

Abstract: Identifying and treating kidney injury in cirrhosis is important. Bile duct ligation (BDL) is a commonly used cholestatic liver disease model. We hypothesized that asymmetric dimethylarginine (ADMA) is involved in BDL‐induced oxidative stress and kidney injury, which can be prevented by melatonin. We also intended to elucidate whether increased ADMA is due to increased protein arginine methyltransferase‐1 (PRMT1, ADMA‐synthesizing enzyme) and/or decreased dimethylarginine dimethylaminohydrolase (DDAH, ADMA‐metabolizing enzyme). Three groups of young rats were studied, sham (N = 7), untreated BDL rats (N = 9), and melatonin‐treated BDL rats (N = 6, BDL + M). Melatonin‐treated BDL rats received daily melatonin 1 mg/kg/day via intraperitoneal injection. One‐third of the young BDL rats died compared with none in the BDL + M group. All surviving rats were killed 14 days after surgery. BDL rats had higher plasma aspartate aminotransferase, alanine aminotransferase, direct and total bilirubin, and ammonia levels than shams. They also had kidney injury characterized by increased tubulointerstitial injury scores and plasma creatinine and symmetric dimethylarginine levels, which melatonin prevented. Plasma ADMA levels were elevated in BDL rats, combined with increased hepatic PRMT1 and decreased renal DDAH activity. In addition, melatonin increased hepatic DDAH2 expression, increased DDAH activity and concomitantly decreased ADMA contents in both the liver and kidney. In conclusion, melatonin therapy decreased mortality and prevented kidney injury induced by BDL via reduction of ADMA (by increasing DDAH activity) and oxidative stress.     

Simultaneous bile duct and portal venous branch ligation in two-stage hepatectomy

Hepatectomy is an effective surgical treatment for multiple bilobar liver metastases from colon cancer;however,one of the primary obstacles to completing surgical resection for these cases is an insufficient volume of the future remnant liver,which may cause postoperative liver failure.To induce atrophy of the unilateral lobe and hypertrophy of the future remnant liver,procedures to occlude the portal vein have been conventionally used prior to major hepatectomy.We report a case of a 50-year-old woman in wh...     

狗肝硬化门脉高压症血浆儿茶酚胺浓度变化的实验研究

本研究通过结扎狗胆总管形成肝硬化门脉高压症的动物模型,对模型形成前后门静脉压力、肝静脉压力、门静脉血流量、肝动脉血流量、门静脉血管阻力,肝动脉血管阻力和门静脉、肝静脉、腹主动脉。下腔静脉四部位血浆儿茶酚胺浓度的变化进行了自身对照性对比研究。结果:①肝硬化形成后门脉压力明显增高,肝静脉嵌塞区也明显增高,门脉血流量减少而肝动脉血流量增加,门脉血管阻力增加而肝动脉血管阻力则下降。这些变化与人类肝硬化门脉高压症相同。②门静脉、肝静脉。腹主动脉和下腔静脉血浆去甲肾上腺素的含量均在门脉高压形成后明显增加。提示肝硬化时血浆去甲肾上腺素的增加可能参与门脉高压症的某些病理生理过程,并进一步支持用 a 受体阻滞剂降低门脉压力和门脉血管阻力,治疗肝硬化食道静脉曲张破裂出血或预防出血。     

The effect of bile duct ligation, bile duct cannulation, and hypothermia on alpha-naphthylisothiocyanate-induced hyperbilirubinemia and cholestasis in rats

The hyperbilirubinemic and cholestatic responses to alpha-naphthylisothiocyanate (ANIT) in the rat were altered by subjecting test animals to various environmental and surgical manipulations. Studies utilizing hypo- and hyperthermic conditions showed that a positive correlation exists between the rectal temperature and the effects of ANIT. In addition, it was observed that ANIT produced an apparent poikilothermic response, in that treated rats were unable to maintain normal rectal temperatures. Bile duct ligation inhibited the cholestatic and altered the hypothermic responses to ANIT treatment. Cannulation of the bile duct prior to ANIT administration significantly inhibited the hyperbilirubinemia and cessation of bile flow. These data demonstrate the importance of an intact enterohepatic circulation and normal body temperature in the actions of ANIT. The effect of the various parameters on the ANIT-induced hyperbilirubinemia and cholestasis suggests the involvement of a biotransformation product of ANIT.     

Dietary glycine blunts liver injury after bile duct ligation in rats

AIM： To investigate the effects of （dietary） glycine against oxidant-induced injury caused by bile duct ligation （BDL）.
METHODS： Either a diet containing 5% glycine or a standard diet was fed to male Sprague-Dawley （SD） rats. Three days later, BDL or sham-operation was performed. Rats were sacrificed 1 to 3 d after BDL. The influence of deoxycholic acid （DCA） in the presence or absence of glycine on liver cells was determined by measurement of calcium and chloride influx in cultivated Kupffer cells and lactate dehydrogenase （LDH） activity was determined in the supernatant of cultivated hepatocytes.
RESULTS： Serum alanine transaminase levels increased to about 600 U/L 1 d alter BDL. However, enzyme release was blunted by about two third in rats receiving glycine. Release of the alkaline phosphatase and aspartate aminotransferase was also blocked significantly in the group fed glycine. Focal necrosis was observed 2 d after BDL. Glycine partially blocked the histopathological changes. Incubation of Kupffer cells with DCA led to increased intracellular calcium that could be blocked by incubation with glycine. However, systemic blockage of Kupffer cells with gadolinium chloride had no effects on transaminase release. Incubation of isolated hepatocytes with DCA led to a significant release of LDH after 4 h. This release was largely blocked when incubation with glycine was performed.
CONCLUSION： These data indicate that glycine significantly decreased liver injury, most likely by a direct effect on hepatocytes. Kupffer cells do not appear to play an important role in the pathological changes caused by cholestasis.