Adenosine Triphosphate in Liver after Partial Hepatectomy and Acute Stress

The Association Between Low Preoperative Phosphate Levels and Postliver Surgery Outcomes-A Single Center Experience

INTRODUCTION

Previous research has demonstrated the impact of postoperative phosphate levels on liver regeneration and outcomes after liver resection surgeries, a potential predictor for regenerative success and liver failure. However, little is known about the association between low preoperative serum phosphate levels and outcomes in liver resections.

METHODS

We performed a retrospective analysis of liver resections performed at our institution. Patients were categorized based on preoperative phosphate levels (low versus normal). Our primary outcome measure was posthepatectomy liver failure.

RESULTS

A total of 265 cases met the study criteria. 71 patients (26.7%) had low preoperative phosphate levels. The incidence of posthepatectomy liver failure was higher in the low preoperative phosphate group (19.2% versus 12.4%). However, after propensity score matching, rates of posthepatectomy liver failure were similar between low and normal preoperative phosphate cohorts (13% versus 14%, P = 0.83).

CONCLUSIONS

Low preoperative phosphate levels were not associated with worse postoperative outcomes in this study. Further studies are warranted to investigate this association and its relevance as a clinical prognostic factor for postoperative liver failure.

Early Postoperative Serum Phosphate Drop Predicts Sufficient Hypertrophy After Liver Surgery

OBJECTIVE

The aim of this study was to assess the impact of postoperative hypophosphatemia on liver regeneration after major liver surgery in the scenario of Associating Liver Partition with Portal vein ligation for Staged hepatectomy (ALPPS) and living liver donation (LLD).

BACKGROUND

Hypophosphatemia has been described to reflect the metabolic demands of regenerating hepatocytes. Both ALPPS and LLD are characterized by an exceptionally strong liver regeneration and may be of particular interest in the context of posthepatectomy hypophosphatemia.

METHODS

Serum phosphate changes within the first 7 postoperative days after ALPPS (n=61) and LLD (n=54) were prospectively assessed and correlated with standardized volumetry after 1 week. In a translational approach, postoperative phosphate changes were investigated in mice and in vitro .

RESULTS

After ALPPS stage 1 and LLD, serum phosphate levels significantly dropped from a preoperative median of 1.08 mmol/L [interquartile range (IQR) 0.92-1.23] and 1.07 mmol/L (IQR 0.91-1.21) to a postoperative median nadir of 0.68 and 0.52 mmol/L, respectively. A pronounced phosphate drop correlated well with increased liver hypertrophy ( P <0.001). Patients with a low drop of phosphate showed a higher incidence of posthepatectomy liver failure after ALPPS (7% vs 31%, P =0.041). Like in humans, phosphate drop correlated significantly with degree of hypertrophy in murine ALPPS and hepatectomy models ( P <0.001). Blocking phosphate transporter (Slc20a1) inhibited cellular phosphate uptake and hepatocyte proliferation in vitro.

CONCLUSION

Phosphate drop after hepatectomy is a direct surrogate marker for liver hypertrophy. Perioperative implementation of serum phosphate analysis has the potential to detect patients with insufficient regenerative capacity at an early stage.

Hypophosphataemia after major hepatectomy and the risk of post-operative hepatic insufficiency and mortality: an analysis of 719 patients

BACKGROUND

Hypophosphataemia after a hepatectomy suggests hepatic regeneration. It was hypothesized that the absence of hypophosphataemia is associated with post-operative hepatic insufficiency (PHI) and complications.

METHODS

Patients who underwent a major hepatectomy from 2000-2012 at a single institution were identified. Post-operative serum phosphorus levels were assessed. Primary outcomes were PHI (peak bilirubin >7 mg/dl), major complications, and 30- and 90-day mortality.

RESULTS

Seven hundred and nineteen out of 749 patients had post-operative phosphorus levels available. PHI and major complications occurred in 63 (8.8%) and 169 (23.5%) patients, respectively. Thirty- and 90-day mortality were 4.0% and 5.4%, respectively. The median phosphorus level on post-operative-day (POD) 2 was 2.2 mg/dl; 231 patients (32.1%) had phosphorus >2.4 on POD2. Patients with POD2 phosphorus >2.4 had a significantly higher incidence of PHI, major complications and mortality. On multivariate analysis, POD2 phosphorus >2.4 remained a significant risk factor for PHI [(hazard ratio HR):1.78; 95% confidence interval (CI):1.02-3.17; P = 0.048], major complications (HR:1.57; 95%CI:1.02-2.47; P = 0.049), 30-day mortality (HR:2.70; 95%CI:1.08-6.76; P = 0.034) and 90-day mortality (HR:2.51; 95%CI:1.03-6.15; P = 0.044). Similarly, patients whose phosphorus level reached nadir after POD3 had higher PHI, major complications and mortality.

CONCLUSION

Elevated POD2 phosphorus levels >2.4 mg/dl and a delayed nadir in phosphorus beyond POD3 are associated with increased post-operative hepatic insufficiency, major complications and early mortality. Failure to develop hypophosphataemia within 72 h after a major hepatectomy may reflect insufficient liver remnant regeneration.

Hepatotrophic factors: implications for diabetes mellitus

In view of the importance of insulin in hepatic cell proliferation and regeneration, disturbances might be expected in these processes in diabetics. The relative importnace of insulin replacement given intraportally rather than subcutaneously is discussed. Results are presented showing that even when normoglycaemia is achieved with peripheral insulin infusion using the 'artificial pancreas' there are still abnormalities in intermediary metabolism. The incidence of cirrhosis in diabetes is reviewed and it is concluded that the evidence is poor for an increase in diabetics. Finally it is shown that in the normal diabetic rat changes are observed after partial hepatectomy consistent with an increase in redox potential within the regenerating liver. Insulin treatment improves redox status but does not completely reverse the changes shown.

Cyclin expression in the atrophying and proliferating lobes of the liver after portal vein branch ligation and hepatectomy in rats

BACKGROUND

Portal vein branch ligation causes atrophy of the portal vein ligated lobes (PVL) and proliferation of the nonligated lobes (PVNL) of the liver. However, the mechanisms underlying atrophy of the PVL and proliferation of PVNL after portal vein branch ligation have not been clarified except that interleukin-6 (IL-6), nuclear factor kappa B (NF-kappaB), signal transducer and activator of transcription 3 (STAT3), and immediate-early gene expression are similarly induced in both the PVL and the PVNL. Thus, it is still unclear what factors cause the subsequent atrophy and proliferation.

MATERIALS AND METHODS

Male Wistar rats were randomly separated into a portal vein branch ligation group and partial hepatectomy group. In the portal vein branch ligation group, the branch of portal vein supplying the median and left lateral lobes of the liver was ligated. In the partial hepatectomy group, the correspondent lobes of the liver were excised. We examined cyclin expression in the PVL and PVNL after portal vein branch ligation in comparison to cyclin expression in the remaining liver (HEP) after partial hepatectomy. Cyclin D1, E, and A mRNA and protein expressions were analyzed by RT-PCR and Western blotting, respectively.

RESULTS

The mRNA and protein expressions of cyclin D1 and A were not up-regulated in the PVL, whereas those in the PVNL and HEP were up-regulated. Cyclin D1 mRNA and protein expressions were significantly lower in the PVL than in the PVNL and HEP at 18 h. The levels of mRNA and protein expression of cyclin A were significantly lower in the PVL than in the PVNL and HEP at 36 h. Liver regeneration, assessed by the relative liver weight, thymidine incorporation into DNA, and proliferating cell nuclear antigen (PCNA) labeling index was delayed significantly in the PVNL compared to that in the HEP. Cyclin D1 mRNA and protein expressions were significantly lower in the PVNL than in the HEP at 12 and 18 h, respectively.

CONCLUSIONS

Cell-cycle progression might be inhibited at G(1)-phase accompanied by impaired cyclin D1 expression in the PVL, which results in atrophy. The fact that liver proliferation of the PVNL is delayed in comparison to that of the HEP is likely due to delayed expression of cyclin D1.

Changes in ultrastructure and the occurrence of permeability transition in mitochondria during rat liver regeneration

Mitochondrial bioenergetic impairment has been found in the organelles isolated from rat liver during the prereplicative phase of liver regeneration. To gain insight into the mechanism underlying this impairment, we investigated mitochondrial ultrastructure and membrane permeability properties in the course of liver regeneration after partial hepatectomy, with special interest to the role played by Ca2+ in this process. The results show that during the first day after partial hepatectomy, significant changes in the ultrastructure of mitochondria in situ occur. Mitochondrial swelling and release from mitochondria of both glutamate dehydrogenase and aspartate aminotransferase isoenzymes with an increase in the mitochondrial Ca2+ content were also observed. Cyclosporin-A proved to be able to prevent the changes in mitochondrial membrane permeability properties. At 24 h after partial hepatectomy, despite alteration in mitochondrial membrane permeability properties, no release of cytochrome c was found. The ultrastructure of mitochondria, the membrane permeability properties and the Ca2+ content returned to normal values during the replicative phase of liver regeneration. These results suggest that, during the prereplicative phase of liver regeneration, the changes in mitochondrial ultrastructure observed in liver specimens were correlated with Ca2+-induced permeability transition in mitochondria.

Improved functional reserve of hypertrophied contra lateral liver after portal vein ligation in rats

BACKGROUND/AIMS

We assessed the functional capacity of hypertrophied liver after portal vein ligation (PL) in a test group of rats compared to a control group (without PL) having the same size liver.

METHODS

The portal veins of the left and median lobes in the test group were ligated in an initial operation. Four days after the PL, the liver volume of the posterior caudate lobe (5%) increased two-fold, accounting for 10% of the liver. Then a 90% hepatectomy was performed, leaving only the hypertrophied posterior caudate lobe. Rats in a sham group underwent a 90% hepatectomy 4 days after having laparotomy, leaving the normal anterior and posterior caudate lobes (10%).

RESULTS

The survival rate for the PL group was significantly higher than for the sham group at 4 days after hepatectomy (56.3 and 26.7%, P<0.05). The regeneration ratio and the proliferating cell nuclear antigen (PCNA) labeling index in the PL group was markedly higher than in the sham group 24h after hepatectomy.

CONCLUSIONS

Hypertrophied liver at 4 days after PL still showed liver regeneration. Regenerating liver provided greater tolerance for extended hepatectomy than normal liver. This is because of the induced rapid regeneration of the remaining liver after hepatectomy.

Metabolic control patterns in acute phase and regenerating human liver determined in vivo by 31-phosphorus magnetic resonance spectroscopy

OBJECTIVE

To elucidate the metabolic changes occurring within hepatocytes during acute phase reaction and liver regeneration.

SUMMARY BACKGROUND DATA

The metabolic events occurring within the liver during the hepatic stress response are poorly understood. The authors used in vivo 31-phosphorus magnetic resonance spectroscopy to study hepatic metabolism after surgical trauma with and without loss of liver cell mass.

METHODS

Three groups were studied: five patients undergoing partial hepatectomy; five patients in whom laparotomy and colonic resection was performed; and five patients treated by thyroidectomy. Hepatic metabolism was evaluated by 31-phosphorus magnetic resonance spectroscopy before surgery and serially thereafter on postoperative days 2, 4, 6, 14, and 28. Estimation of liver volume by magnetic resonance imaging and blood sampling for biochemistry were performed at the same time points.

RESULTS

The authors found that alterations in hepatocyte phospholipid metabolism occurred after surgery that were correlated with changes in circulating acute phase proteins. Liver regeneration after hepatectomy was also associated with a derangement in energy metabolism, measured by a decrease in the ratio of ATP to its hydrolysis product inorganic phosphate. The depleted energy status was mirrored in biochemical indices of liver function, and restitution paralleled the course of restoration of hepatic cell mass.

CONCLUSIONS

These findings indicate that changes in liver metabolism after surgery reflect the magnitude of tissue injury and the quantity of functioning liver cells. Acute phase responses dominate the initial recovery period at the expense of less important endergonic functions. When liver parenchyma is lost, the acute phase reaction is maintained and further supported by a rapid replenishment of hepatocytes, which can even be considered a continuation of acute phase physiology. Modulation of liver function within the framework of overall hepatic energy economy is one mechanism for matching energy supply with increased demands during these processes.

Beneficial effects of arterialization of the portal vein on extended hepatectomy

BACKGROUND

Extended hepatectomy may result in postoperative liver failure. The aim of this study was to evaluate the effects of arterialization of the portal vein on oxygen supply, hepatic energy metabolism and liver regeneration after extended hepatectomy.

METHODS

Portal haemodynamics were evaluated 0 or 10 days after arterialization of the portal vein in three experimental groups: 85 per cent partial hepatectomy, 85 per cent partial hepatectomy 10 days after arterialization of the portal vein and 85 per cent partial hepatectomy 10 days after ligation of the hepatic artery. Survival rates, weight of the regenerating liver, levels of adenine nucleotides and hepatic energy charge were assessed.

RESULTS

Arterialization of the portal vein caused a significant increase in partial pressure of oxygen and oxygen saturation. Portal blood flow 10 days after arterialization was significantly increased. Survival rate and weight of the regenerating liver in the group with arterialization of the portal vein were significantly higher than those in the other two groups. The group with arterialization of the portal vein showed the highest levels of adenosine 5'-triphosphate.

CONCLUSION

The increase in portal blood flow and oxygen supply produced by arterialization of the portal vein has beneficial effects on hepatic energy metabolism and liver regeneration, and leads to improved survival after experimental extended hepatectomy.

Release of matrix proteins from mitochondria to cytosol during the prereplicative phase of liver regeneration

70% partial hepatectomy (PH) in the rat causes a release, into the cytosolic fraction, of mitochondrial matrix proteins, namely the mitochondrial isoform of aspartate aminotransferase (mAAT) and malate dehydrogenase (MDH), during the first 24 h after PH, when no growth of the residual liver is observed. After this time interval, the weight of the liver starts to increase and the normal weight is reached at 96 h after PH. This proliferative phase is characterized by a progressive recovery of the normal levels of intramitochondrial activities of mAAT and MDH. Mitochondria isolated at 24 h after PH show a membrane permeabilization to sucrose accompanied by a release of matrix enzymes; both are blocked by cyclosporin A. These results suggest an alteration of mitochondrial membrane integrity, during the prereplicative phase of liver regeneration, with the occurrence of an increased permeability that allows the passage into the cytosol of matrix enzymes.

Advantage of preoperative portal vein occlusion for hepatectomy that exceeds portal vein occluded lobes

BACKGROUND

The purpose of our study was to examine the effect of preoperative portal vein (PV) occlusion on hepatic reserve function after extended hepatectomy that is an excision of areas beyond the PV occluded lobes.

METHODS

Male Wistar rats were divided into three groups and underwent a two-stage operation: a PVL-hepatectomy group (ligation of the PV [PVL] of the left and median lobes followed by hepatectomy of the right lobes together with the PV occluded lobes), a sham-88% hepatectomy group (sham operation without PVL followed by hepatectomy corresponding to the lobes excised in the PVL-hepatectomy group), and a sham-67% hepatectomy group (sham operation followed by hepatectomy of the left and median lobes to approximate the volume excised in the PVL-hepatectomy group). In all subjects, hepatectomy was carried out 7 days after the PVL or sham operation. On days 0, 1, 2, and 3 after hepatectomy, liver weight, histologic elements, DNA synthesis rates, energy charge, adenine nucleotides, and lipoperoxide levels of the remaining liver were determined.

RESULTS

In the sham-88% hepatectomy group, the volume of resected liver was 88.2% +/- 0.5%. In the PVL-hepatectomy group it was 69.1% +/- 0.8%, although anatomically identical lobes were excised. At the time of hepatectomy, DNA synthesis, hepatic concentrations of adenine nucleotides and lipoperoxide, and serum liver function tests showed similar results in all three groups. The survival rate 3 days after hepatectomy was significantly low (53%) in the sham-88% hepatectomy group, whereas it was 100% in the PVL-hepatectomy and sham-67% hepatectomy groups. The gain in liver weight per day was significantly lower in the sham-88% hepatectomy group than in the other two groups. The decline in hepatic energy charge after hepatectomy was less, with less activated DNA synthesis, in the PVL-hepatectomy group compared with the sham-88% hepatectomy and sham-67% hepatectomy groups. Lipoperoxide concentration in the PVL-hepatectomy group was significantly lower than that in the sham-88% hepatectomy and sham-67% hepatectomy groups.

CONCLUSIONS

Preoperative PV occlusion not only increases the remaining liver volume but also is advantageous to hepatic reserve after hepatectomy that exceeds PV occluded lobes.

Serum hyaluronic acid level reflects volume and ATP levels of the liver after extended hepatectomy with and without preoperative portal vein occlusion

The purpose of this study was to examine the hypothesis that the serum hyaluronic acid (HA) level reflects the volume and adenosine triphosphate (ATP) levels of the liver after extended hepatectomy (ExHx) with and without preoperative portal vein occlusion (PVO). Rats were randomly divided into two groups, PVO-ExHx and sham-ExHx. At the first stage, they underwent PVO or sham surgery by an occlusion of the portal vein supplying the left lateral and median lobes or by similar manipulation but without PVO, respectively. Seven days after first-stage surgery, both groups received ExHx exceeding portal vein-occluded lobes, which was the excision of the left lateral, median, and right lateral lobes of the liver reported as a 90% hepatectomy model. On Days 0, 1, 2, and 3 after ExHx, the serum HA concentrations, liver weights, and hepatic ATP levels were determined. Liver volumes were restored to similar levels in both groups, but restoration was faster in the PVO-ExHx group because preoperative PVO allowed the excised liver less volume. Lower serum HA levels were significantly associated with significantly higher hepatic ATP levels and with a lower mortality rate in the PVO-ExHx group. The serum HA level correlated significantly (P < 0.001) with the liver weight and hepatic ATP level. The serum HA level serves as a proxy for clinically important parameters following major hepatic surgery.

Hepatic adenine nucleotides and microsomal cholesterol 7 alpha-hydroxylase activity in the obstructed and freely draining lobes of the liver after selective bile duct obstruction

BACKGROUND

The effect of selective bile duct obstruction (SBDO) on hepatic reserve function of the bile duct obstructed (BDO) and nonobstructed freely draining (FD) lobes of the liver is obscure.

METHODS

The bile duct branches draining from the left lateral and median lobes of the liver were ligated for 4 and 10 days in rats, and hepatic reserve functions in BDO and FD lobes were assessed by microsomal cholesterol 7 alpha-hydroxylase activities and by hepatic adenine nucleotides and energy charge levels. The values were compared with those in the sham-operated control liver. Cholesterol 7 alpha-hydroxylase activities were determined by gas-liquid chromatography--mass spectrometry, and hepatic adenosine triphosphate (ATP), adenosine diphosphate (ADP), and adenosine monophosphate (AMP) levels with high-pressure liquid chromatography.

RESULTS

The histological examination of the BDO lobes showed proliferation and formation of new bile ductules and fibrous connective tissues linking portal areas. Microsomal cholesterol 7 alpha-hydroxylase activities, hepatic energy charge and each adenine nucleotide level did not differ between FD and BDO lobes, and the values were similar to those in the sham-operated liver.

CONCLUSIONS

Selective bile duct obstruction shows no adverse effects on microsomal and mitochondrial functions in both the BDO and FD lobes of the liver.

Influence of chronic liver damage on regeneration of the organ in rats

To investigate the influence of chronic hepatic damage on liver regeneration, a 70% hepatectomy was carried out in male BDE rats in which chronic hepatic damage had been induced by i.m. injection of 0.1 ml CCl4/100 g b. w. twice a week for 4 weeks. After resection, we examined adenine nucleotide concentration in the remaining liver tissues, also body weight and wet and dry weight of the liver. The total adenine nucleotide concentration fell 6 h after resection from 2.89 +/- 0.22 mumol/g to 2.03 +/- 0.15 mumol/g and then recovered on the 3rd postoperative day. However, control animals showed lowest values 3 h after resection, and had already begun to recover at 6 h. Energy charges fell 3 h after liver both groups to the lowest values, but recovery was slower in the animals with chronic liver damage. These observations suggest that in animals with hepatic damage regeneration is delayed in the initial post-resection period. However, 5 days after resection the wet and dry weights of the liver were completely normalized and there was no difference between the two groups, i.e., 5 days after 70% liver resection we could not find any delayed regeneration tendency in animals with chronic liver damage.

Correlation between rat liver regeneration and mitochondrial energy metabolism

The time course of changes in mitochondrial energy metabolism during liver regeneration, following partial hepatectomy, is analyzed. For 24 h after surgical operation, a lag phase in the time course of the growth of liver is observed. In this period mitochondria showed a decrease of: (1) the respiratory control index; (2) the rate of oxidative phosphorylation; (3) the amount of immunodetected beta-F1 and F01-PVP subunits of F0F1-ATP synthase. No decrease, but instead a small increase in the content of mRNA for beta-F1 was observed in this phase. After this lag phase the growth of liver started, the content of mRNA for beta F1, as well as the level of immunodetected mitochondrial beta-F1 and F01-PVP subunits, increased and oxidative phosphorylation recovered. Analysis of the relative beta F1 protein/mRNA ratio indicates a decrease of beta F1 translational efficiency which remained low up to 72 h after partial hepatectomy and reached the same ratio of control at 96 h. It is concluded that the regenerating capability of rat liver is correlated with the efficiency of oxidative phosphorylation.

Changes in phosphatidylethanolamine metabolism in regenerating rat liver as measured by 31P-NMR

31P-NMR spectra of regenerating rat liver in vivo show increases in resonance intensities in the phosphomonoester (PME) region and decreases in the phosphodiester (PDE) region as early as 12 h post partial hepatectomy, which return to normal by 8 days. The compounds primarily responsible for these changes have been identified in perchloric acid extracts as the phosphomonoester phosphoethanolamine and the phosphodiester glycerophosphoethanolamine (GPE), indicating altered phosphatidylethanolamine metabolism. A corresponding increase in diacylglycerol (DAG) levels during regeneration indicates a possible role for a phosphatidylethanolamine-specific phospholipase C in cellular proliferation. These results suggest that changes in phospholipid metabolites previously associated with neoplastic tissue can also be induced by normal tissue undergoing rapid cellular proliferation. The spectral changes observed in the regenerating rat liver are similar to changes seen in spectra from the livers of human patients in several disease states, indicating that 31P-NMR may allow non-invasive study of cell turnover in liver disease.

Availability of energy substrates during liver regeneration in malnourished rats

A retarded liver regeneration rate during malnutrition has previously been reported. To explore the mechanisms, some energy substrates were studied during liver regeneration and malnutrition. Forty-one rats were allocated to one of three groups (G): GI were normally nourished rats, which were partially hepatectomized; GII were semistarved rats, which were partially hepatectomized; and GIII were normally nourished rats, which were sham-operated. Biopsy specimens were taken from the liver at the time of partial hepatectomy and when they were killed after 48 h of regeneration. The samples were analysed for adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), glycogen, lactate, and pyruvate, and energy charge potential (ECP) was calculated. ATP, ECP, and glycogen levels were decreased in the malnourished group before the resection. After 48 h of regeneration all values were unchanged in the normally nourished group, whereas ATP, ADP, and ECP were increased in the malnourished group compared with the initial values. The lactate/pyruvate quotient was increased in malnourished rats compared with normal rats. The results suggest that the energy supply is not a limiting factor for the reduced regeneration rate seen in malnourished animals.

Altered hepatic energy status in chlordecone (Kepone)-potentiated CCl4 hepatotoxicity

Previous studies have demonstrated that increased intracellular calcium, depletion of glycogen, and suppressed hepatocellular division resulting in progression of hepatic lesion without recovery are associated with chlordecone (CD)-potentiated CCl4 hepatotoxicity. Since these phenomena are indicative of compromised hepatic energy status, the present studies were designed to investigate this possibility. Neither hepatic ATP content nor mitochondrial Mg2(+)-ATPase was altered significantly in rats maintained on diets contaminated with either CD (10 ppm), or phenobarbital (PB; 225 ppm) alone for 15 days. Similarly, CCl4 (100 microL/kg) administration alone did not alter hepatic ATP levels or mitochondrial Mg2(+)-ATPase activity in rats maintained on a normal diet. However, CCl4 administration to CD pretreated rats resulted in significantly decreased hepatic ATP content as early as 1 hr (36%), and this decrease was irreversibly progressive with time (81% at 6 hr). Oligomycin-sensitive Mg2(+)-ATPase was decreased significantly only starting at 6 hr (21%) after CCl4 administration, indicating that depletion of ATP at early time points was most likely due to rapid utilization consequent to toxic events. CCl4 administration to mirex or PB pretreated rats resulted in a smaller decrease in ATP levels (18-24%) only at 24 hr, returning to normal levels by 36-48 hr, in accord with rapid recovery from limited liver injury. These findings indicate that CCl4 administration to CD but not to PB or mirex pretreated rats results in a severely compromised energy status of the liver. The progressive and early depletion of liver ATP and the inhibition of Mg2(+)-ATPase in CD + CCl4 treated rats indicate the association of compromised energy status with altered Ca2+ homeostasis, depletion of glycogen, and suppressed cell division in CD-potentiated CCl4 toxicity.

Effect of cyclosporine on oxidative phosphorylation and adenylate energy charge of regenerating rat liver

The effect of cyclosporin A (CyA) on regenerating liver was investigated in subtotal hepatectomized rats treated with CyA in terms of mitochondrial phosphorylative activity, hepatic energy charge, and serum bilirubin levels. In the CyA-treated hepatectomized group, the energy charge decreased from normal control value of 0.857 to 0.782 at 6 h after hepatectomy. The decreased energy charge, however, gradually increased and returned to 0.842 at 48 h after hepatectomy with no significant changes being observed between CyA-treated and untreated hepatectomized groups. Phosphorylation rate in the CyA-untreated group increased to 142% of the normal control at 24 h and then decreased to 114% at 48 h after hepatectomy. By contrast, phosphorylation rate in the CyA-treated group increased to 144% of the normal control at 24 h, but remained at the high value of 132% (P less than 0.01; compared to the CyA-untreated group) even at 48 h after hepatectomy. Serum total bilirubin levels in the CyA-treated group were significantly higher than those in the CyA-untreated group during all experimental periods. We conclude that CyA does not exert a direct detrimental effect on mitochondrial function and that, despite the marked hyperbilirubinemia induced by CyA, the mitochondrial phosphorylative activity increases adaptively to provide sufficient energy for enhanced ATP-utilizing reactions in an early process of liver regeneration.

Increased rate of purine biosynthesis in rat liver after bilateral adrenalectomy

In bilaterally adrenalectomized rat liver the increased rate of de novo purine synthesis was shown by the increased [14C]glycine incorporation into hepatic acid-soluble purines with unchanged rapidly miscible glycine pool size and its turnover rate and by the increased rate of chasing of radiolabeled purines. At 24 h after adrenalectomy, the rate of de novo purine synthesis increased by 70%, 5-phosphoribosyl-1-pyrophosphate (PRPP) content increased by 200%, the specific activity of amidophosphoribosyltransferase (EC 2.4.2. 14; ATase) did not change, ATP and GTP showed a 33 and 24% decrease, and AMP and ADP showed a 245 and 38% increase. Combined, the metabolic pool size data reflected an unchanged total inhibitory potential on ATase. Replacement with corticosterone acetate for 24 h partially restored some of these abnormalities. These results suggest that the increase in the rate of de novo purine synthesis in adrenalectomized rat liver is secondary to increased catabolism of purine ribonucleotides and mediated by increased PRPP concentrations.

Hepatic regeneration and metabolism after partial hepatectomy in normal rats: effects of insulin therapy

The effect of insulin therapy on liver regeneration has been studied in normal fed rats 12, 24 and 48 h after partial hepatectomy. Dry weight of regenerating liver increased between 12 and 48 h after partial hepatectomy and was unaffected by insulin therapy. [6-3H] Thymidine uptake peaked at 24-h (24.7 +/- 2.4% of total liver cells) and insulin treatment had no additional effect. At 12-h after partial hepatectomy, hepatic [ATP] was decreased 15%, while [ADP] and [AMP] were increased 47% and 83% respectively compared with sham-operated animals. Partial hepatectomy also caused an increase in hepatic [triglyceride], a decrease in hepatic [glycogen] and an increase in the levels of glucose and several glycolytic intermediates. The hepatic redox ratios, [lactate]:[pyruvate] and [3-hydroxybutyrate]:[acetoacetate], were elevated. Insulin therapy had only minor effects on hepatic adenine nucleotide levels, intermediary metabolite concentrations or intrahepatic redox ratios after partial hepatectomy. These findings suggest a decreased hepatic intracellular energy state in regenerating liver; insulin therapy in normal rats does not influence this metabolic change nor the regenerative response.

Compartmentation of intracellular nucleotides in mammalian cells

The important role of nucleotides in cellular metabolism requires that serious consideration be given to the question of the homogeneity or inhomogeneity of nucleotide pools in cells. The purpose of this review is to summarize the existing evidence for compartmentation of nucleotide pools, discuss the limitations of this evidence, and to discuss the implications of compartmentation for the interpretation of nucleotide concentration measurements. Evidence for nucleotide compartmentation comes from the following types of evidence: compartmentation of RNA precursors; compartmentation of deoxynucleoside triphosphates; mitochondrial compartmentation; the existence of tightly bound nucleotides; pools derived from alternative synthetic routes; compartmentation in cyclic nucleotide metabolism; channeling in the synthesis of pyrimidine nucleotides; and others. The types of evidence adduced for compartmentation will be considered critically and in detail, and alternative explanations considered, as well. Implications of the data and hypotheses on nucleotide compartmentation for the interpretation of nucleotide pool measurements in various types of experiments will be discussed.

Inhibitory effects of jaundice on regenerating liver

The effects of partial hepatectomy on the energy charge (ATP + 1/2ADP/ATP + ADP + AMP) and mitochondrial oxidative phosphorylation were studied in normal and jaundiced rats. In normal rats and energy charge levels of the remnant liver decreased only slightly with a rise in the phosphorylative activity of the mitochondria at an early stage after hepatectomy, and then rapidly returned to normal. In jaundiced rats subjected to the common bile duct ligation the energy the energy charge levels of the liver decreased to approximately 0.800 from 0.849 of normal value, though their mitochondrial oxidative phosphorylation was within normal limits. In jaundiced rats the energy charge levels of the remnant liver after partial hepatectomy decreased markedly without a return toward normal. The mitochondrial phosphorylative activity increased to only about 50% of hepatectomized normal rats after partial hepatectomy. More than 70% of jaundice rats died within 24 hours after partial hepatectomy. It was suggested that the jaundice inhibits an enhancement of ATP generation to provide sufficient energy for high energy demand rather than the enery-requiring biosynthetic process in an early process of liver regeneration.