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

Therapeutic effect of prostaglandin E1 in monocrotaline-induced pulmonary arterial hypertension rats

Pulmonary arterial hypertension (PAH) is a severe pulmonary vascular disease characterized by sustained increase in pulmonary arterial pressure and excessive thickening and remodeling of distal small pulmonary arteries. During disease progression, PAH include increase in mean pulmonary arterial pressure, right ventricular (RV) enlargement, increased pulmonary vascular resistance, and smooth muscle hypertrophy in pulmonary arterioles. Several anti-PAH therapies targeting various pathways involved in PAH progression have been approved by the Food and Drug Adminstration. However, many of the currently available anti-PAH drugs suffer from a number of limitations, including short biological half-life, and poor pulmonary selectivity. Prostaglandin E1 (PGE1) is a potent vasodilator with selectivity toward pulmonary circulation when it is administered via the pulmonary route. However, PGE1 has a very short half-life of 5–10 minutes. Therefore, we hypothesized that long-term effect of PGE1 could reduce mal-adaptive structural remodeling of the lung and heart and prevent ventricular arrhythmias in monocrotaline-induced rat model of PAH. Our results revealed that PGE1 reduced ventricular hypertrophy, protein expressions of endothelin-1 and endothelin receptor A, and the expression of fibrosis. These results support the notion that PGE1 can improve the functional properties of RV, highlighting its potential benefits for heart and lung impairment.

Effectiveness of intraportal prostaglandin E1 administration after liver transplantation

PURPOSE

Prostaglandin E1 (PGE1) has been used to improve hepatic blood flow and to reduce ischemia reperfusion injuries of allografts in liver transplantation. However, PGE1 undergoes extensive metabolic clearance in the pulmonary and splanchnic circulation during intravenous administration. We analyzed the effect of intraportally administered PGE1.

METHODS

Sixty living-donor liver transplant recipients received continuous infusions of PGE1 for 10 days immediately after the reperfusion of the allografts. Of them, 40 recipients received PGE1 intravenously (IV group) via the internal jugular vein, and 20 recipients received PGE1 intraportally (IP group) through a catheter in the inferior mesenteric vein. Data were collected for 3 weeks postoperatively.

RESULTS

The IP group exhibited lower initial aspartate aminotransferase and alanine aminotransferase levels compared with the IV group. However, no apparent differences were recognized in the serum albumin, total bilirubin, alkaline phosphatase, r-glutamyl transpeptidase, or prothrombin time levels between the 2 groups. Chylorous ascites were observed more frequently in the IP group. There was no difference in portal venous flow measured by Doppler sonogram between the 2 groups during the first postoperative week.

CONCLUSION

This study demonstrated that intraportal administration of PGE1 had a better cytoprotective effect against hepatocellular damage than intravenous administration, although it did not have additional benefits for perihepatic hemodynamics.

Omega 3 - Omega 6: What is right for the liver?

Linoleic and alpha-linolenic acids are the fatty acids designated as "essential" since they are not synthesized by mammalian cells and must be provided in the diet. The recent dietary shift towards the consumption of n-6 (omega-6) at the expense of n-3 (omega-3) polyunsaturated fatty acids (PUFAs) is thought to be a primary cause of many diseases related to the Western diet. The body converts linoleic acid to arachidonic acid and derives eicosapentaenoic acid from alpha-linolenic acid. Ideally the effects of these fatty acids and their eicosanoid derivatives are tailored to the specific biological needs of the body. The balance between n-3 and n-6 PUFAs is essential for metabolism and maintenance of the functions of both classes. The availability of n-3 long chain PUFAs plays a major role in regulating both fat accumulation and its elimination by the liver. Derangement of hepatic n-6:n-3 PUFA ratio impacts on the histological pattern of fatty liver through modulation of the amount of intrahepatic lipids. Moreover, the influence of PUFAs and their eicosanoid products on hepatic microcirculation and ischemia/reperfusion injury has been demonstrated in many studies. This concise review article will focus on the role of PUFAs and eicosanoids in hepatic steatosis, microcirculation and ischemia/reperfusion injury.

The effect of intraportal prostaglandin E1 on adhesion molecule expression, inflammatory modulator function, and histology in canine hepatic ischemia/reperfusion injury

BACKGROUND

Prostaglandin E1 (PGE1) is known to protect the liver from I/R, however, the mechanism of cytoprotection is not well understood. This study investigates the effect of intraportal infusion of PGE1 in a warm liver ischemia/reperfusion (I/R) model on cytokines, adhesion molecules and liver structure.

MATERIALS AND METHODS

Twenty dogs underwent laparotomy under general anesthesia. PGE1 (0.02 microg\kg\min) was perfused through the portal vein in the PGE1 group (n = 10), or a similar volume of Ringer's solution in the control group (n = 10) for 15 min. Liver ischemia was induced by hepatic artery and portal vein occlusion and PGE1 was infused via the portal vein for 60 min. The occlusion was released and PGE1 infusion recommenced for 30 min. Blood and liver biopsies were sampled at baseline, 60 min ischemia, and 30 min reperfusion and assessed for transaminases, cytokines, adhesion molecules, and electron microscopy.

RESULTS

PGE1 infusion significantly reduced transaminases TNF-alpha, sICAM-1, sP-selectin, and sE-selectin on ischemia and reperfusion. PGE1 reduced hepatocytic degeneration, portal and central ICAM-1 expression, central and sinusoidal VCAM-1 expression, portal and central P-selectin expression, and portal and sinusoidal E-selectin expression on reperfusion.

CONCLUSION

Intraportal PGE1 infusion reduced I/R injury and was associated with down-regulation of ICAM-1, VCAM-1, P-selectin, and E-selectin on reperfusion.

Efficacy of continuous infusion of prostaglandin E1 through the superior mesenteric artery against ischemic liver cell necrosis after hepatic artery occlusion

BACKGROUND

Hepatic artery occlusion (HAO) can cause severe ischemic liver injury, especially after an interruption of collateral circulation after extensive hepatobiliary surgery. To minimize a decrease in oxygen delivery after HAO, a continuous infusion of prostaglandin (PG)E1 through the superior mesenteric artery (SMA) was studied in comparison with other infusion routes.

METHODS

Twenty-four pigs were assigned to four groups: HAO without PGE1 (control group); HAO with PGE1 (0.02 microg/kg/min, continuously) through the jugular vein (intravenous group); HAO with PGE1 through the portal vein (PV group); and HAO with PGE1 through the SMA (SMA group). PV flow, hepatic oxygen delivery, and serum aspartate aminotransferase were measured after infusion. In addition, 72-hr survival rates were observed, and histologic examination of liver specimens was performed.

RESULTS

PGE1 infusion through the SMA seems to affect PV flow and elevate the oxygen content of portal blood, whereas other routes of administration do not. The reduction of hepatic oxygen delivery after HAO was 51% in the control group, 46% in the intravenous group, and 49% in the PV group, whereas it was limited to 13% in the SMA group. Serum aspartate aminotransferase values 24 hr after HAO were lowest in the SMA group, which was statistically significant, as confirmed by histology. The survival rate of animals was 100% in the SMA group and 33% in the other three groups.

CONCLUSION

These findings indicate that continuous PGE1 infusion through the SMA may prove useful in clinical settings to prevent liver damage after HAO.

Effect of short-term administration of prostaglandin E1 on viability after ischemia/reperfusion injury with extended hepatectomy in cirrhotic rat liver

The cytoprotective effect of prostaglandin E(1) (PGE(1)) has been demonstrated experimentally and clinically against hepatic ischemia and reperfusion injury and against the effects of partial hepatectomy in both individual and combined models of noncirrhotic livers. Cirrhotic livers are more vulnerable to ischemia/reperfusion injury during hepatectomy than are noncirrhotic livers, and postoperative malfunctioning complicates life with multiple organ failure. Cirrhotic livers with tumors have mostly been treated conservatively because extended hepatectomy with induced ischemia during surgery is impossible. The purpose of our study was to document postoperative surgical adaptation in inoperable cases with improved survival after extended hepatectomy in a rat model of cirrhosis treated by PGE(1). Cirrhosis was induced by intraperitoneal injections of 1% dimethylnitrosamine. The liver was subjected to 15 minutes of total ischemia by occluding the hepatoduodenal ligament. Hepatectomy was performed during ischemia. Pretreatment with PGE(1) (0.4 microg/kg/min) (or without it in the controls) was given for 15 minutes by intravenous infusion prior to inducing ischemia and during reperfusion. Portal venous flow (PVF) and liver tissue blood flow (LTBF) were measured during reperfusion. At the end of 60 minutes of reperfusion, venous blood was collected for liver function tests. The animals were followed up regarding survival for 48 hours. The PVF and LTBF were significantly improved in the PGE(1) group. The blood chemical analysis indicated that PGE(1) significantly suppressed posthepatectomy liver dysfunction. Most importantly, PGE(1) treatment markedly improved the survival rate, from 42% in the controls to 75% in the test animals at 24 hours after hepatectomy and from 17% in the controls to 58% in the test animals at 48 hours. We concluded that short-term administration of PGE(1) makes extensive hepatectomy possible under ischemic conditions in cirrhotic livers.

Appraisal of intra-arterial infusion of prostaglandin E1 in patients undergoing major hepatic resection report of four cases

In order to reduce risk for postoperative acute liver failure, prostaglandin E1 (PGE1) was administered either from the hepatic artery (HA) or the superior mesenteric artery (SMA) in four high-risk cases undergoing major hepatic resection. Two cases were subjected to HA PGE1 infusion for 3 or 4 days after surgery at a rate of 0.01 microg/kg/min. Both patients had hepatocellular carcinoma (HCC) associated with chronic hepatitis, and ICG R15 was 17.6% and 14.5%, respectively. Right hemihepatectomy and extended right hemihepatectomy were performed. Serum total bilirubin (T. Bil.) peak value was 2.2 mg/100 ml in Case 1 and 2.1 mg/100 ml in Case 2. In Case 1, decreased bile flow was observed immediately after cessation of PGE1. The other two cases were subjected to SMA PGE1 infusion for 5 or 6 days after surgery at the same rate. In Case 3, right hemihepatectomy was performed for HCC on a cirrhotic liver four weeks after right portal vein embolization, in which preoperative ICG R15 was 19.0%. Peak T. Bil level was 3.7 mg/100 ml with uneventful postoperative course. In Case 4 with a huge cholangioma, right trisegmentectomy was performed. Peak serum T. Bil level was 1.7 mg/100 ml in this uneventful postoperative course. In Case 3 and Case 4, portal blood flow, measured by Doppler ultrasonography, was markedly increased by PGE1 infusion. From these results, intra-arterial PGE1 infusion might be useful in prevention of postoperative liver failure after major hepatic resection.

Warm ischemia and reperfusion injury in diet-induced canine fatty livers

BACKGROUND

Fatty liver is associated with primary nonfunction after liver transplantation, contributing a shortage of suitable liver grafts. Because extensive investigation of mechanisms underlying such nonfunction has been limited largely to rodents, we made a new fatty liver model in dogs and studied primary nonfunction after warm ischemia.

METHODS

We developed a diet rich in fat but deficient in choline to induce fatty change in canine liver and investigated effects of 60 min of warm ischemia and reperfusion in dogs with such fatty livers.

RESULTS

Microscopically evident steatosis increased with duration of dietary manipulation (up to 12 weeks), as did hepatic total lipid and triglyceride levels. No dog with >30% of steatotic hepatocytes, >445 mg/g hepatic total lipid or >145 mg/g hepatic triglyceride survived after 60 min of warm ischemia. Arterial ketone body ratios decreased and blood endotoxin increased after reperfusion in nonsurvivors. The main histologic finding in livers of nonsurvivors was marked sinusoidal congestion.

CONCLUSIONS

Damage to hepatocytes and nonparenchymal cells after warm ischemia and reperfusion was thought to be closely related to sinusoidal microcirculatory disturbances in fatty livers. The canine fatty liver model reported here may be useful in studying the pathology of primary nonfunction and in establishing criteria for allowable degrees of fatty change in potential liver grafts.

Experimental study of the effect of intraportal prostaglandin E1 on hepatic blood flow during reperfusion after ischaemia and hepatectomy

BACKGROUND

Prostaglandin E1 (PGE1) has protective effects experimentally and clinically in individual models of hepatic ischaemia-reperfusion injury and of partial hepatectomy. The present study investigated the effects of intraportal administration of PGE1 on hepatic blood flow, systemic arterial pressure and long-term animal survival after 60 min of total liver ischaemia followed by 70 per cent partial hepatectomy in rats.

METHODS

Total liver ischaemia was induced by occluding the hepatoduodenal ligament for 60 min. PGE1 0.5 microg per kg per min was infused intraportally for 15 min before inducing ischaemia and for 120 min after ischaemia in the treatment group. Normal saline was infused in the control group. During ischaemia 70 per cent partial hepatectomy was performed. Portal venous flow (PVF), peripheral tissue blood flow (PTBF) and hepatic artery flow were measured before and after ischaemia. Serum biochemical analysis was carried out at 1, 3 and 24 h, and 7 and 14 days; and liver histology at 1 and 24 h, and 7 days after reperfusion. Survival was followed for 1 year.

RESULTS

Intraportal infusion of PGE1 significantly improved PVF and PTBF without affecting the systemic arterial pressure. Long-term survival was significantly higher in the PGE1 group. Serum aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase levels decreased significantly, and 2-h bile flow was significantly improved, in the PGE1 group. Histological examination revealed significant portal venous congestion, sinusoidal congestion, fatty degeneration and tissue necrosis 24 h and 7 days after reperfusion in the control group.

CONCLUSION

PGE1 has a protective effect against liver damage when the liver is injured by warm ischaemia and reperfusion followed by partial resection.

Protective effect of prostaglandin E1 against ischemia/reperfusion-induced liver injury: results of a prospective, randomized study in cirrhotic patients undergoing subsegmentectomy

BACKGROUND/AIMS

The cytoprotective effects of prostaglandin E1 on livers suffering from ischemia/reperfusion injury in the clinical setting are unproved. These effects were examined, focusing on inflammatory cytokine and nitric oxide metabolism.

METHODS

Twenty-four cirrhotic patients with hepatocellular carcinoma undergoing subsegmentectomy under ischemia induced only by Pringle's maneuver were divided into two groups (patients given prostaglandin E1 by injection and untreated controls) and postoperative results were compared. Peripheral blood was taken perioperatively and the plasma aminotransferase, cytokines and nitrate/nitrite levels of the two groups were compared. Two liver specimens were taken from each patient, one before ischemia and the other after hepatectomy, and the levels of inducible nitric oxide synthase and cytokine mRNAs and proteins were analyzed.

RESULTS

Although no apparent differences were recognized in postoperative complications or duration of postoperative hospital stay between the groups, the perioperative plasma aminotransferase level was significantly lower in the prostaglandin E1 group. Significant differences were also seen in interleukin-6 and nitrate plasma levels during the observation period and the interleukin-6 protein levels in the liver supernatants after hepatectomy in the two groups. In contrast, no significant differences were apparent between the interleukin-1 beta and tumor necrosis factor-alpha plasma levels of the two groups. The corrected fluorescence activities of interleukin-6 and inducible nitric oxide synthase mRNAs in the liver after hepatectomy correlated significantly. No interleukin-1 beta or tumor necrosis factor-alpha mRNAs or proteins were detected.

CONCLUSIONS

Prostaglandin E1 exerted hepatoprotective effects on livers suffering from ischemia/reperfusion injury, and interleukin-6 might play an important role in these effects.

Experimental ischemic liver injury and regeneration over 3 months: histological observations in the rat

Liver histopathology of segmental portal ischemia occurring over a long-term period has not been previously described. For these reasons histological changes in the rat liver were studied from 1 h to up to 90 days after a left lateral and middle segmental portal obstruction. Within 3 h, the hepatocytes showed glycogen depletion in Rappaport zones 1 and 2 and pericentral and central lobular congestion of sinusoids and veins, whereas within 3 days, vein thrombosis appeared in the center of the lobule and liver necrosis was observed in Rappaport zones 2 or 3 or both, followed by restitutio ad integrum of the liver lobule morphology after 20-40 days. These results can be explained in light of two conditions occurring in the rat liver: (i) the peculiar low sensitivity of the liver to O2 debit and the protective or vasoactive effects used during hypoxia; and (ii) the sinusoidal network as a collateral source of the hepatic vascular system. Therefore, morphological assessment of this arteriolar and sinusoidal system, implicated in assuring efficient collateral blood supply in the rat liver with portal ischemia, is essential for understanding the mechanisms behind a natural and timely repair of ischemic injuries in the human liver.

Efficacy of intraportal infusion of prostaglandin E1 to improve the hepatic blood flow and graft viability in porcine liver transplantation

BACKGROUND

Prostaglandin E1 (PGE1) has been reported to have a protective effect in experimental and clinical models of liver damage. The aim of this study was to elucidate the effects of the intraportal infusion of PGE1 on hepatic blood flow and graft viability after orthotopic liver transplantation in pigs.

METHODS

First, the hepatic arterial flow (HAF), portal venous flow (PVF), and liver tissue blood flow (LTBF) were measured during the continuous intravenous or intraportal infusion of PGE1. Second, two groups of pigs underwent orthotopic liver transplantation: group A, untreated controls; and group B, animals that received intraportal PGE1 for 2 hr after vascular reconstruction of the allograft. Changes in HAF, PVF, LTBF, and hepatic function were measured.

RESULTS

The intraportal infusion of PGE1 significantly increased HAF and had no effect on blood pressure, PVF, or LTBF. In group B, HAF and LTBF increased significantly with time. In group A, HAF remained unchanged and a decrease in LTBF was observed. Group B exhibited a higher arterial ketone body ratio and a greater bile flow compared with group A. A significant elevation in serum glutamic oxaloacetic transaminase concentration was observed in group A, but not in group B.

CONCLUSIONS

This study demonstrates that the intraportal infusion of PGE1 improves hepatic allograft blood flow, predominantly through an effect on HAF, and may improve graft viability after orthotopic liver transplantation.

Prostaglandin E1 resuscitates hepatic organic anion transport independent of its hemodynamic effect after warm ischemia

Prostaglandin E1 (PGE1) is a promising agent against ischemic liver damage, but direct evidence of the benefit to intrinsic hepatocyte function has been lacking. We demonstrate here that organic anion transport can be supported by treatment with PGE1 even at a lower dose which does not affect hepatic microcirculation in rabbits with liver inflow occlusion. Near-infrared spectroscopy was applied to directly measure hepatic clearance of indocyanine green (ICG), an exogenous organic anion, and to estimate microcirculation as measured by oxygen saturation and the content of hemoglobin in the sinusoid. Also, morphological changes in microtubules, the cytoskeleton which is known to be associated with organic anion transport, and energy status, as measured by adenine nucleotide levels, were observed. ICG removal rate in hepatocytes decreased significantly from 0.100 +/- 0.018 to 0.027 +/- 0.019 min-1 (mean +/- SD, P < 0.01) by 60-min warm ischemia, whereas the value increased to 0.082 +/- 0.030 min-1 (P < 0.05) when PGE1 was given at a dose of 0.05 microgram/kg/min. The treated livers also showed early reorganization of microtubules, as well as amelioration of ATP resynthesis after reperfusion. However, there were no significant differences in intraoperative changes in oxygen saturation and the content of hemoglobin in the sinusoid between PGE1-treated and untreated groups, indicating that the influence of PGE1 at this dose on hemodynamic changes is not considerable. These results indicate that PGE1 resuscitates an inherent hepatocyte function of organic anion transport on reperfusion after warm ischemia and suggest that the benefit could be attributed solely to direct action on hepatocytes.