Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:APRD00530 (Portal)
 4,208 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Renal handling of sodium was studied in five dogs where an end-to-side portacaval fistula was constructed prior to the induction of cirrhosis with DMN. Such a model permits the effects of cirrhosis to be studied separately from the consequences of portal hypertension. Three control animals without cirrhosis maintained normal liver and kidney function and remained in sodium balance for as long as 8 weeks following surgery. In the five cirrhotic dogs, urinary sodium retention preceded ascites formation and was independent of hyperaldosteronism, hypoalbuminemia, hepatic ischemia, or decreased renal perfusion. Portal venous pressure remained normal in all cirrhotic dogs, and the splanchnic area remained free of venous collaterals. Plasma volume expansion also preceded ascites formation, and this variable increased by 8.4% (p less than 0.05) following 6 days of sodium retention. These temporal relationships between sodium retention, expanded plasma volume, and ascites formation are similar to those observed in ordinary cirrhotic dogs previously studied in this laboratory. Total plasma volume increased by 13.2% (p less than 0.05) when measured during the ascitic phase of cirrhosis. However, when the splanchnic and nonsplanchnic ("effective") components of plasma volume were measured by an exclusion technique, the ratio of these components to total plasma volume was not different from that observed in normal dogs. Thus no preferential consignment of retained salt and water had occurred. We conclude that urinary sodium retention in cirrhotic dogs occurs independently of portal hypertension or augmented splanchnic vascular capacity and is associated with expansion of the effective plasma volume, even though ascites is present.
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PMID:Renal sodium retention and ascites formation in dogs with experimental cirrhosis but without portal hypertension or increased splanchnic vascular capacity. 62 53

Coagulation mechanisms were examined in the dog after a 70 per cent hepatectomy and the additional effect of varying periods of ischemia on the liver remnant. Dogs were submitted to a 70 per cent partial hepatectomy, and the liver remnant was rendered ischemic by occluding the vascular inflow. Portal decompression during ischemia was accomplished by allowing portal venous flow through the lobes subsequently resected. Dogs in the control group, those undergoing hepatectomy alone and those undergoing hepatectomy together with 60 minutes of ischemia time exhibited a fall in hemoglobin and hematocrit values, a transient leukocytosis, a small increase in kaolincephalin clotting time and a decline in platelet count but no significant thrombocytopenia. Prothrombin time was changed in dogs undergoing hepatectomy, but this was not affected by ischemia. The characteristic rise in plasma fibrinogen postoperatively was abolished, and fibrinogen levels were lower in dogs undergoing hepatectomy alone and fell significantly in dogs subjected to 30 to 60 minutes of ischemia of the liver remnant. Factors V and VII were decreased after hepatectomy, and Factor V was more severely reduced after 30 to 60 minutes of ischemia. There was no overt bleeding tendency. In ten dogs, the liver remnant was subjected to ischemia for 75 minutes. Four of these died within three days of operation, two with severe hypoglycemia and two with postoperative bleeding. All six surviving dogs exhibited gross coagulation defects. Prothrombin time rose, kaolin-cephalin clotting time increased and platelets fell to a greater degree than in any of the other dogs. Plasma fibrinogen level showed a profound fall, as did Factor V, the magnitude of these changes being greater than after a shorter period of ischemia. Factor VII was also decreased, but this did not appear to be related to the ischemic interval. In the clinical situation in which intrinsic coagulation mechanisms are shown to be impaired, treatment with Factor V and VII concentrates may be the best way of correcting the coagulation defect.
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PMID:The mechanism of impaired coagulation after partial hepatectomy in the dog. 93 55

Portal circulation was reduced to 50-60% for one hour by partial occlusion of the superior mesenteric artery for the purpose of studying the relationship between reperfusion injury, bacterial translocation and multiple system organ failure. Forty dogs were divided randomly into four groups, and 1 x 10(10)/kg E. coli O111B4 were fed to each animal 12 hours before operation. Group I constituted the controls, in which sham operations were performed. The experimental procedure was completed in all the animals of the other three groups. Rubia yunnanensis, an anti-oxidant, was given to group III. Amikacin was given to group IV. The results showed that group II was characterized by bacteremia, hypoxemia, and hypotension as compared with group I. The levels of superoxide dismutase (SOD) in the whole blood were markedly lowered and malondialdehyde (MDA) values significantly elevated in group II after reperfusion compared with group I. Plasma levels of anaphylatoxin C5a and B2 (TXB2) were significantly raised in group II beginning with the reperfusion when compared with groups I, III and IV. Pathological changes in the intestine, liver and lung were remarkable only in group II, including acute necrosis of the intestinal mucosa, granulocyte infiltration, hemorrhage and edema of the lung, degenerative changes of myocardial and hepatic cells, and bacterial invasion of the blood, liver and lung. These results suggested that bowel ischemia and reperfusion may promote gut barrier failure and bacterial translocation, then contribute to the development to multiple system organ failure (MSOF) by allowing bacteria or endotoxin normally contained within the gut to reach the portal and systemic circulations where it fuels the septic process. Oxygen free radicals, anaphylatoxin and thromboxane may be potential factors in the development of gut barrier failure and MSOF.
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PMID:Bacterial translocation and multiple system organ failure in bowel ischemia and reperfusion. 180 29

Mechanical ventilation with positive end-expiratory pressure (PEEP) diminishes gut and hepatic blood flow and redistributes cardiac output away from the splanchnic circulation. This flow-limited environment can aggravate underlying hypoperfusion and ischemia in the postinjury setting. To examine the effects of low dose dopamine on a lung injury PEEP model of gut hypoperfusion, six anesthetized, splenectomized canines were instrumented with arterial, pulmonary artery, portal vein, and hepatic vein catheters. Electromagnetic flow probes were placed around the hepatic artery and portal vein for continuous flow measurements. Gut and hepatic blood flow, oxygen delivery, oxygen consumption, and extraction ratio were calculated at four time points: baseline, 1 hr after lung injury with oleic acid, 1 hr after ventilation with 10 cm H2O PEEP, and 1 hr after the continuous infusion of dopamine. Portal flow and gut oxygen delivery fell significantly with the infusion of PEEP. These values returned to near baseline levels with the addition of dopamine. Gut oxygen extraction increased from 16 +/- 2% to 35 +/- 3% with PEEP but returned to near baseline with dopamine (20 +/- 4%, P less than 0.01 compared to PEEP). We conclude that dopamine improves blood flow and oxygen delivery to the gut in this flow-limited model. This may preserve splanchnic physiology during PEEP ventilation for acute lung injury.
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PMID:The effect of low dose dopamine on gut hemodynamics during PEEP ventilation for acute lung injury. 190 74

Hepatic artery blood flow changes to buffer portal blood flow alterations, maintaining a constant total hepatic blood flow. Portal blood flow is regulated by preportal organs, such as intestine, pancreas and spleen. The liver plays an important role as a blood reservoir for cardiovascular homeostasis. Hepatic blood volume is mobilized actively to the systemic circulation by sympathetic stimulation. Sinusoid, the specialized capillary of the liver, and Disse's space are separated by endothelial cells, which have numerous fenestrations, allowing effective exchanges of solutes between hepatocytes and blood. Unidirectional blood flow in the acinus causes functional differences of hepatocytes according to the lobular zones. Although the majority of anesthetics decreases liver blood flow in a dose dependent manner, halothane inhibits hepatic arterial buffer response, while isoflurane and narcotics preserve it. Energy depletion, cellular acidosis, alteration of calcium homeostasis and superoxide-induced membrane damage, are all implicated as important factors for ischemia-induced liver injury. A better understanding of ischemia-induced derangements of cell function will lead to more rational preservation of the liver cells in the future.
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PMID:[Hepatic circulation and anesthesia]. 202 91

Acute lung injury characterized by increased microvascular permeability is one feature of multiple-organ system failure and the adult respiratory distress syndrome. Intestinal ischemia-reperfusion injury has been linked to this type of acute lung injury. The purpose of these experiments was to examine the pathogenic mediators that link the two processes, with particular emphasis on the roles of endotoxin and tumor necrosis factor alpha (TNF alpha). Previously described characteristics of the acute lung injury in this rat model of intestinal ischemia-reperfusion include pulmonary neutrophil sequestration, depletion of lung tissue ATP, alveolar endothelial cell disruption, and increased microvascular permeability. Plasma levels of TNF in the systemic circulation of sham-operated animals and those with intestinal ischemic injury less than 60 minutes in duration were very low or undetectable. Intestinal ischemia for 120 minutes was associated with TNF elevation to 1.19 +/- 0.50 U/mL. Reperfusion for periods of 15 and 30 minutes generated 5- to 10-fold increases in circulating TNF levels (6.61 +/- 3.11 U/mL, p greater than 0.05 and 10.41 +/- 5.41 U/mL, p = 0.004 compared to sham); however this increase in circulating TNF was transient and largely cleared within 60 minutes after initiating reperfusion. Portal vein endotoxin levels were found to increase significantly before the appearance of TNF in systemic plasma, suggesting that gut-derived endotoxin may induce TNF release from hepatic macrophages into the systemic circulation. Anti-TNF antibody attenuated the increase in pulmonary microvascular permeability in this preparation but did not prevent pulmonary neutrophil sequestration. These observations suggest that endotoxin and TNF have pathogenic roles in this acute lung injury, but that mechanisms of adherence of neutrophils to endothelial cells independent of TNF may be involved. The accumulation of neutrophils in the lung but the prevention of a vascular permeability increase in the presence of antibody to TNF may imply an in vivo role for TNF in the process of neutrophil activation. These studies provide additional evidence of the importance of the endogenous inflammatory mediators in the development of systemic injury in response to local tissue injury.
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PMID:Evidence for tumor necrosis factor-induced pulmonary microvascular injury after intestinal ischemia-reperfusion injury. 217 68

Various blood flow disturbances in intraabdominal digestive organs were studied clinically and experimentally from a viewpoint of vascular surgery. Acute gastric mucosal lesion may occur due to ischemia and reperfusion injury of the gastric mucosa. Bleeding from stomach ulcer may be rarely caused by consumption coagulopathy along with aortic aneurysm. Heparin therapy was successful to interrupt it. Gastrectomy is not indicated for such condition but aneurysm should be repaired. Portal vein reconstruction for the radical resection of hepatic, biliary and pancreatic cancers should be carefully made, because early or late stenosis occurs frequently, and they may connect to early or late morbidities or mortalities. On the other hand, resection and replacement of the suprarenal vena cava invaded by the retroperitoneal malignant tumor may be safely carried out. For the acute mesenteric arterial occlusion, early diagnosis and arterial reconstruction are essential to save catastrophe. Positive Doppler sound on the vasa recta seems to be the most reliable parameter for assessing bowel viability. Approach from the proximal large arteries is recommended for uncontrollable intraperitoneal bleeding.
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PMID:[Blood flow disturbance in digestive organs--a viewpoint of vascular surgery]. 258 8

The present study examines the effect of chlorpromazine and biliary drainage in cholestatic rats. The time course of portal blood flow was studied 24, 48, and 72 h and seven days after bile duct ligation. Portal blood flow decreased after 72 h. Chlorpromazine reduced biliary hydrostatic pressure in sham-operated control rats, but 24-h obstruction was sufficient to prevent this effect in cholestatic rats. The drug ameliorated the mitochondrial and cell membrane function of cholestatic rats before and after drainage. The data present further support for the role of ischemia in cholestasis.
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PMID:Effect of chlorpromazine and biliary drainage on portal blood flow and mitochondrial function during extrahepatic cholestasis. 262 53

Serum bile acids and their fractions in the systemic and portal vein were measured after liver ischemia of 0, 30, 60, and 90 minutes with extracorporeal venous bypass in 20 dogs. The following results were obtained: 1) Total concentration of bile acids in the serum rapidly increased during the ischemic phase because of extinction of enterohepatic circulation due to flow of portal blood into the systemic circulation. 2) Portal blood flow decreased after recirculation of the liver, and this decrease was more severe in the 90-minute ischemic group than in the 30- and 60-minute groups. 3) After recirculation, increased bile acids were taken up by hepatocytes, and their concentrations in the systemic vein decreased markedly. The 90-minute ischemic group had a significantly slower rate of decrease compared to the 30- and 60-minute groups. This was due to its significantly lower portal blood flow rate. 4) Hepatocyte dysfunction was suggested in the 90-minute ischemic group, since the uptake of bile acids into the liver, especially dihydroxy- and deconjugated bile acids, significantly decreased. These results indicate that measurement of serum bile acids and their fractions is useful for estimating the liver function after liver ischemia.
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PMID:[Experimental study on the changes of bile acids and their fractions after liver ischemia]. 281 41

The intra- and early postoperative courses of 142 consecutive patients who underwent liver resections using vascular occlusions to reduce bleeding were reviewed. In 127 patients, the remnant liver parenchyma was normal, and 15 patients had liver cirrhosis. Eighty-five patients underwent major liver resections: right, extended right, or left lobectomies. Portal triad clamping (PTC) was used alone in 107 cases. Complete hepatic vascular exclusion (HVE) combining PTC and occlusion of the inferior vena cava below and above the liver was used for 35 major liver resections. These 35 patients had large or posterior liver tumors, and HVE was used to reduce the risks of massive bleeding or air embolism caused by an accidental tear of the vena cava or a hepatic vein. Duration of normothermic liver ischemia was 32.3 +/- 1.2 minutes (mean +/- SEM) and ranged from 8 to 90 minutes. Amount of blood transfusion was 5.5 +/- 0.5 (mean +/- SEM) units of packed red blood cells. There were eight operative deaths (5.6%). Overall, postoperative complications occurred in 46 patients (32%). The patients who experienced complications after surgery had received more blood transfusion than those with an uneventful postoperative course (p less than 0.001). The length of postoperative hospital stay was also correlated with the amount of blood transfused during surgery (p less than 0.001). On the other hand, there was no correlation between the durations of liver ischemia of up to 90 minutes and the lengths of postoperative hospital stay. The longest periods of ischemia were not associated with increased rates of postoperative complications, liver failures, or deaths. There was no difference in mortality or morbidity after major liver resections performed with the use of HVE as compared with major liver resections carried out with PTC alone, although the lesions were larger in the former group. It is concluded that the main priority during liver resections is to reduce operative bleeding. Vascular occlusions aim at achieving this goal and can be extended safely for up to 60 minutes.
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PMID:Vascular occlusions for liver resections. Operative management and tolerance to hepatic ischemia: 142 cases. 291 65


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