Role of mitochondrial enhancement in maintaining hepatic energy charge level in endotoxin shock

Activation of hepatic branched-chain alpha-keto acid dehydrogenase complex by tumor necrosis factor-alpha in rats

Tumor necrosis factor-alpha (TNFalpha) promotes oxidation of branched-chain amino acids (BCAA). BCAA catabolism is regulated by branched-chain alpha-keto acid dehydrogenase (BCKDH) complex, which is regulated by phosphorylation-dephosphorylation of the E1alpha subunit at Ser293. BCKDH kinase is responsible for inactivation of the complex by phosphorylation. In the present study, we examined the effects of TNFalpha administration on hepatic BCKDH complex and kinase in rats. Rats were intravenously administered with 25 or 50 microg TNFalpha/kg body weight 4 h prior to sacrifice. The TNFalpha treatment at both doses elevated the activity state (percentage of the active form) of BCKDH complex from 22% to 69% and 86%, respectively, and the amount of phospho-Ser293 on the E1alpha subunit in each group of rats corresponded inversely to the activity state of BCKDH complex. The TNFalpha treatment of rats significantly decreased the activity as well as the bound form of BCKDH kinase. These results suggest that the decrease in the bound form of kinase is involved in the mechanism responsible for TNFalpha-induced activation of the BCKDH complex.

Contribution of serotonin to liver injury following canine small-intestinal ischemia and reperfusion

Intestinal ischemia and reperfusion (I/R) has been shown to be associated with multiple organ damages. Serotonin (5-hydroxytriptamine; 5-HT), which is synthesized in the enterochromaffin cells in the intestine and stored in platelets, is known to play an important role in platelet aggregation and vasoconstriction and may ultimately enhance such organ injuries. The purpose of this study was to investigate the association between liver damage and 5-HT levels in the liver after intestinal I/R. The entire canine small intestine, isolated on a vascular pedicle that consisted of the proximal superior mesenteric artery and superior mesenteric vein, was subjected to 4-h ischemia by clamping these vessels and the marginal arteries supplying the proximal and distal ends of the small intestine. Hepatic blood flow, liver tissue blood flow, bile flow rate, and hepatic venous ketone body ratio (HVKBR) were measured before and at the end of intestinal ischemia and at 5, 15, and 30 min, and 1 and 2 h after reperfusion. 5-HT levels in plasma of the portal vein and hepatic vein were assayed at the same intervals. Time-matched, sham-operated animals served as controls. Intestinal I/R significantly decreased the liver tissue flow, bile flow rate, and HVKBR. Compared to those in controls, 5-HT levels in the portal vein and hepatic vein were markedly increased after reperfusion. Furthermore, intravenous administration of 5-HT receptor antagonists attenuated the liver dysfunction after intestinal reperfusion. These results suggest that intestinal I/R induces continuous disturbance of hepatic microcirculation, leading to liver dysfunction, and that 5-HT may be implicated as one of the mediators of liver dysfunction after intestinal I/R.

Hepatic phosphatidylcholine hydroperoxide content in noncirrhotic, cirrhotic, and antioxidant-treated rats with endotoxemia

Hepatic phosphatidylcholine hydroperoxide (PCOOH) was studied intensively to delineate its role in the altered pathophysiology of liver failure associated with endotoxemic shock. Endotoxemia was induced by cecal ligation and puncture (CLP) in three models using rats. Model 1 consisted of normal healthy rats; model 2, cirrhotic rats; and model 3, rats treated with catalase and superoxide dismutase (SOD). Samples were taken before CLP, then 12 h and 24 h following CLP. A progressive and significant increase in serum endotoxin was seen in all models; however, a significantly low energy charge (EC) and high PCOOH were seen in models 1 and 2, whereas no change was observed in model 3. The regional blood flow remained unchanged throughout the experiment in models 1 and 3, but not in model 2. An initial increase in alpha-tocopherol was seen in model 1. The survival rate was markedly better in model 3 than in models 1 or 2. The fall in EC corresponded to the increase in serum endotoxin as well as to the increase in tissue PCOOH in models 1 and 2. It was more likely that the elevated lipid peroxidation in model 1 resulted from endotoxemia rather than from tissue hypoperfusion. The early increase in alpha-tocopherol that occurred in models 1 and 2, but not in model 3, indicated the antiradical defense response to oxidative injury. Thus, antioxidant therapy significantly improved the survival rate and tissue adenine nucleotide level in spite of the increased serum endotoxin level.

The beneficial effect of phosphocreatine accumulation in the creatine kinase transgenic mouse liver in endotoxin-induced hepatic cell death

Purpose. The purpose of this study was to investigate the relationship between hepatic energy status and liver injury during sepsis, using transgenic mice which express creatine kinase in the liver catalyzing the phosphocreatine/creatine system. Methods. Creatine kinase transgenic mice were fed with normal rodent chow or chow containing 10% creatine for 5 days. Lipopolysaccharide (0.2 mg/kg) combined with d-galactosamine (600 mg/kg) was administered intraperitoneally. Results. Eighty percent of the creatine-fed transgenic mice had survived at 48 h post-d-galactosamine and lipopolysaccharide administration, compared with none of the normally fed transgenic mice. Hepatic phosphocreatine and ATP levels in the normally fed transgenic mice were significantly lower than those in the creatine-fed transgenic mice before and after lipopolysaccharide combined with d-galactosamine was administered. Massive hepatic hemorrhagic necrosis with apoptosis was seen in response to d-galactosamine and lipopolysaccharide in normally fed transgenic mice. These results are consistent with a significant increase in serum aminotransferase at 8 h. In contrast, there were faint necrotic changes in the liver with minimal cellular infiltration in creatine-fed transgenic mice. Conclusions. Maintenance of hepatic ATP levels protects from sepsis-induced liver injury and mortality.

Assessment of liver function: pre- and peritransplant evaluation

Liver transplantation has been demonstrated to be a successful therapeutic modality for patients with end-stage liver disease. The high rate of survival for an otherwise terminal condition has resulted in significant expansion of the indications and diseases treated by this procedure, and is hampered only by the limited numbers of organs available for transplantation. Efforts in clinical and laboratory medicine should be directed to identify candidates who would benefit most from this procedure, to provide better means for accurate assessment of liver reserve and the appropriate timing for transplantation, to identify quality liver grafts that would have the potential to tolerate cold preservation and reperfusion injury, and to assist in accurate monitoring of graft function immediately after transplantation. The aim of this manuscript is to describe the existing pathways for clinical and laboratory assessment of pretransplant residual liver function, the donor liver graft, and immediate posttransplantation function.

Gut and liver coordinated metabolic response following major torso injury

Major trauma provokes a stress response which is mediated, in part, via glucagon, catecholamines, and cortisol. These stress hormones modulate the choice of energy substrate for various tissues. While glucose and fatty acids are considered the preferred fuels, ketone bodies (26/ATP/mole) may be a viable alternative. In this study, we measured the concentrations of acetoacetate and beta-hydroxybutyrate (3-OHB) in the portal as well as systemic circulations of 10 critically injured patients (revised trauma score = 6.8 +/- 0.5, injury severity score = 27 +/- 3) during the first 5 postoperative days. At 6 hr postinjury, 3-OHB was elevated in the portal system (0.34 +/- 0.01 mM) while depressed systemically (0.09 +/- 0.02 mM), indicating that the gut was capable of ketogenesis. In contrast, at 24 hr, 3-OHB rose systemically (0.39 +/- 0.02 mM) while decreasing in portal blood (0.09 +/- 0.01 mM) implying gut ketone consumption. Moreover, the systemic ketone body ratio became elevated at 24 hr, suggesting an enhanced liver energy status. In summary, we believe ketogenesis is stimulated by major trauma. Initially, the gut supports ketone concentration in the systemic circulation, whereas, by 24 hr, the gut becomes a ketone consumer and the liver maintains circulating levels.

Alterations in hepatic mitochondrial function during total parenteral nutrition in immature rats

To evaluate the effects of total parenteral nutrition (TPN) on hepatic mitochondrial function in immature rats, changes in hepatic energy charge levels and oxidative phosphorylation rates of hepatic mitochondria were studied along with the examination of serum chemical test. Male Wistar rats weighing 30 to 45 g were used and randomized into TPN (n = 8), enteral (n = 7), and control groups (n = 8). Parenteral and enteral groups were fed with TPN solution containing 19.3% dextrose, 3.19% amino acids, 1.05% fat emulsion, minerals and vitamins, and the control group with rat chow. The number of calories per kilogram per day was 550 x 1/4 on the 1st day, 550 x 1/2 on the 2nd, 550 x 3/4 on the 3rd, and 550 x 1 on the 4th day, based on the body weight on the 1st day. After the 5th day, 550 Kcal/kg/day was given, based on the body weight of the respective day. After 13-day feeding, hepatic energy charge (EC), phosphorylation rate (PR) of hepatic mitochondria and serum chemical examination were carried out. EC was 0.871 +/- 0.016 in the control group, 0.830 +/- 0.019 in the enteral, and 0.785 +/- 0.011 in TPN group (p less than 0.001, compared with control group). PR was 138.9 +/- 1.9, 133.0 +/- 6.7, 111.0 +/- 4.3, respectively, (p less than 0.05, compared with control and enteral groups). There was no difference between the three groups on SGOT, SGPT, and total bilirubin. TPN group showed a deterioration of hepatic phosphorylation rate and energy charge in spite of normal serum transaminase levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of temporary portal vein arterialization: the minimum arterialized blood flow for maintaining liver viability

The effect of temporary portal vein arterialization (PVA) on hepatic energy metabolism was investigated by changes in the arterial blood ketone body ratio (KBR) and hepatic energy charge (EC) level in 17 dogs. The KBR decreased markedly after clamping the hepatic hilar vessels combining mesocaval shunt and remained at a low level throughout hepatic ischemia. After PVA, the KBR was rapidly restored and maintained at sufficient levels. EC at 60 min after arterialization also recovered to the preclamping level. By reducing the arterial shunt flow, the critical point of arterialized blood flow for maintaining the KBR at high levels was assessed to be about 10% of the total hepatic blood flow (THBF). These findings demonstrate that temporary PVA is an effective method for maintaining the functional capacity of the liver, and that the minimum arterialized blood flow needed to preserve liver viability is only about 10% of the total hepatic blood flow.

Influence of colloidal carbon phagocytosis as a metabolic load on the hepatic energy metabolism in rats

The influence of phagocytosis on hepatic energy metabolism was investigated in rats injected with colloidal carbon. Following injection of 6 mg colloidal carbon per 100 g body wt (BW) the hepatic energy charge potential (ECP) remained unchanged. However, oxidative phosphorylation of the isolated mitochondria (PR) increased significantly to 120 and 124% of the control at 1 and 3 hr, respectively, and returned to the normal range at 6 hr. The pyruvate level rose to 195 and 150% at 3 and 6 hr. The lactate level was elevated to 195 and 143% at 3 and 6 hr. Following injection of 20 mg colloidal carbon per 100 g BW, the ECP decreased from 0.865 to 0.783 at 1 hr, but recovered to the normal range thereafter. The PR increased more markedly to 135% at 1 hr, concomitant with an elevation of the ketone body ratio. At 3 hr it remained elevated at 118%, but returned to the normal level at 6 hr. The pyruvate and lactate levels increased to more than 250% at 1 and 3 hr. At 6 hr, the lactate level returned to the control level, but the pyruvate level showed still higher level than the control. These results indicate that phagocytosis exerts an acute metabolic load on the total liver. It was tentatively proposed that parenchymal and nonparenchymal cells in the liver have interrelation in the energy metabolism, and that an enhancement of hepatocellular mitochondrial phosphorylative activity occurs to assist the accelerated metabolism due to phagocytosis.

The changes in arterial keton bodies during upper abdominal surgery

The relationship between the arterial keton body ratio (AKBR: acetoacetate/Beta-hydroxybutyrate) and the plasma hormone activities were studied under a general anesthesia using enflurane group (group G) and a GO + Epidural group (group E) with continuous glucose loading (10 g.hr(-1)) during partial gastrectomy. In both groups, the AKBR increased significantly during the operation. The plasma insulin activity was significantly positively correlated with the AKBR and it was negatively correlated with log (Beta-hydroxybutyrate) in both groups. We could not find any significant difference of the AKBR between group G and group E. Our results indicate that the plasma insulin activity affects the arterial keton body ratio and that the AKBR must be evaluated considering the plasma hormone activity, especially insulin activity during the operation.

Influence of piecemeal necrosis on the compensatory increase of mitochondrial respiratory enzymes of the tumour-bearing liver: clinical study of 53 surgical cases

The relationships between histological findings, adaptively increased cytochrome a(+a3) levels in chronic liver disease and complications after hepatectomy were studied in order to clarify the mechanism of mitochondrial derangement. The liver specimens of 53 hepatectomized patients were randomly evaluated by three independent hepatopathologists and were compared with cytochrome a(+a3) levels in the biopsied liver, the extent of operation and postoperative complications. The cytochrome a(+a3) concentrations did not show any significant difference between cases of chronic hepatitis and liver cirrhosis nor groups classified by regeneration. Severity of piecemeal necrosis was categorized into three groups: group A--minimal (n = 20); group B--moderate (n = 19); and group C--severe (n = 14). There were significant differences (P less than 0.01) in cytochrome a(+a3) concentrations between the groups (A: 99 +/- 9; B: 135 +/- 6; C: 155 +/- 10 pmol/mg of mitochondrial protein). Extensive hepatectomy, involving segmentectomy or more, was frequently complicated (four of nine, 44.4%) in group C, whereas there were few complications (two of 16, 12.5%) in group A cases in which extensive hepatectomy was performed. Evidence will be presented which will show that deranged liver function, as indicated by cytochrome a(+a3) levels, is closely correlated with piecemeal necrosis. This may be attributed to the damage of periportal hepatocytes which are the main sites of oxidative phosphorylation.

Influence of hypoxia on mitochondrial function and energy status in CCl4-induced cirrhotic rat liver

The influence of hypoxia on hepatic mitochondrial function and energy status was studied in normal and carbon tetrachloride (CCl4)-induced cirrhotic rats. Under hypoxemia of 50 mm Hg-PaO2, hepatic energy status was suppressed both in normal and cirrhotic rats. After the reversal of hypoxia, it was completely restored in normal rats concomitant with a rapid elevation of hepatic mitochondrial redox state (overshoot phenomenon) and increase in the mitochondrial oxidative phosphorylative activity. By contrast, in cirrhotic rats, such an enhancement of mitochondrial function was not observed. It was clarified that cirrhotic liver mitochondrial function was not observed. It was clarified that cirrhotic liver mitochondria have little capacity to respond to the hypoxic stress. A lower resistance to hypoxic episode in cirrhotics might be attributable to the absence of mitochondrial enhancement which is a compensatory mechanism for the deranged energy metabolism of the liver.

Current perspectives on septic shock

Although septic shock may be initiated by invading microbes, it is the metabolic and immunologic host responses that determine the true pathophysiology of this common critical care illness. Currently, septic shock therapeutics emphasize empiric and symptomatic treatment. Biochemical elucidation of the septic process will ultimately result in specific interventions for this ominous intensive care syndrome.

Biochemical effects of acute stress on energy metabolism in liver damaged rats

Rats having a non-necrotic damaged liver or a necrotic damaged liver produced by D-galactosamine administration were restrained in water for 0.5, 1, 2, 4, 6, 8 and 12 hours. Serial changes in intrahepatic energy metabolism were compared with those in normal liver. Energy charge, which represents the degree of equilibrium between the energy producing and consuming systems, and cyclic AMP, an intracellular messenger mediating the action of hormones, showed biphasic increases before and after 2 hr in the damaged livers. The lactate/pyruvate ratio, which reflects the cytosolic redox state, markedly increased at 0.5 hr in the damaged livers but returned to the pre-stress level after 1 hr in the non-necrotic damaged liver and after 4 hr in the necrotic damaged liver, showing a transient reduced state. The beta-hydroxybutyrate/acetoacetate ratio, which represents the mitochondrial redox state, decreased at 0.5 hr and returned to the pre-stress level at 1 hr in the non-necrotic damaged liver, exhibiting a transient oxidized state. However, in the necrotic damaged liver, the value decreased at 0.5 hr remained low thereafter, demonstrating a persistent oxidized state. These findings show that, in severely damaged liver, stress has more marked effects on hepatic energy metabolism.

Short-term changes in blood ketone body ratios in the phase immediately after hepatic artery embolization: their clinical significance

Changes in arterial and hepatic venous blood ketone bodies were investigated following transcatheter hepatic artery embolization (THAE) in patients with hepatocellular carcinoma. Acetoacetate/ beta-hydroxybutyrate ratio (ketone body ratio) in arterial blood was positively correlated with those of hepatic venous blood (r = 0.960, p less than 0.001), which reflects the mitochondrial redox potential in the embolized lobe. Nine cirrhotic patients were classified into three groups according to the changes in arterial blood ketone body ratio following THAE: Type A without decrease to below 0.7; Type B with a transient decrease to below 0.7, followed by its restoration within 5 hours; and Type C with decrease to below 0.7 without recovery within 5 hours. There were no serious complications in Type A and B patients. By contrast, severe sepsis and hepatic failure developed in Type C patients, possibly due to the extended embolization of both lobes. It is suggested that THAE can be successfully performed even in severely cirrhotic patients, as long as the embolized area is restricted to one lobe. In addition, changes in arterial blood ketone body ratios can give early information about the likely consequences of the THAE procedure just performed.

Adenylate energy charge and cytochrome a (+a3) in the cirrhotic rat liver

In the cirrhotic rat liver induced by phenobarbitone and carbon tetrachloride, adenylate energy charge, mitochondrial oxidative phosphorylation, and respiratory enzyme concentrations were studied along with serum albumin concentrations. Cytochrome a (+a3) concentrations of the liver increased with the severity of cirrhosis and were negatively correlated with the ATP-synthesizing ability per unit of cytochrome a (+a3). These changes were associated with the decrease in hepatic energy charge. Such decreased energy charge may be responsible for the decreased serum albumin level in the cirrhotic rat. It is suggested that such falls in hepatic energy charge may be one of the most important factors contributing to the decreased functional reserve of cirrhotic patients.

Changes in acetoacetate/beta-hydroxybutyrate ratio in arterial blood following hepatic artery embolization in man

Acetoacetate/beta-hydroxybutyrate ratio in the hepatic venous blood was compared to the ratios in arterial blood and peripheral venous blood in hypoxic state following right hepatic artery embolization in 5 patients with liver cancer. Ketone body ratios in right hepatic venous blood were positively correlated with those in arterial blood (r = 0.960, p less than 0.001), but not with those in peripheral venous blood. The free NAD+/NADH ratio of the liver mitochondria, which is reflected by the ketone body ration in hepatic venous blood, can be evaluated by the ketone body ratio in the arterial blood.

Ketogenesis during sepsis in relation to hepatic energy metabolism

The concentrations of acetoacetate, beta-hydroxybutyrate, and adenine nucleotides, and the mitochondrial phosphorylative activities, induced by cecal ligation and punctured in the liver of septic rats, were determined. The concentrations of glucose, free fatty acids (FFA), and free amino acids in arterial blood were also studied along with ketone body concentrations. Hepatic energy charge levels decreased from 0.84 to 0.77 at 12h after the induction of sepsis (P less than 0.01) and to 0.60 at 18h (P less than 0.001). Mitochondrial phosphorylative activity was enhanced at 6h (P less than 0.001) and decreased at 18h later. Ketone body concentrations in the liver and the arterial blood decreased concomitant with the decrease in hepatic energy charge. The mitochondrial redox state increased significantly at 12 and 18h after the induction of sepsis (P less than 0.01) concomitant with a marked decrease in the concentrations of ketone bodies (P less than 0.01). Blood glucose levels remained within normal limits except for a transient increase at 6h, but plasma FFA levels decreased (P less than 0.01). The plasma concentrations of aromatic amino acids (P less than 0.001), proline, and alanine (P less than 0.05) increased slightly at 18h. It is suggested that the ketogenic capacity of the liver is inhibited during sepsis, but that the liver maintains gluconeogenesis at relatively normal levels until a more advanced stage of sepsis.