Determination of cytochromes in human liver contaminated with hemoglobin

Kinetic analysis of impaired work-cost performance in jaundiced rabbit liver

Impairment of energy metabolism was studied in jaundiced rabbit liver by kinetic analysis of energy transfer function. Free cytosolic ADP (ADPf), as calculated from the measured components of the glyceraldehyde-3-phosphate dehydrogenase and 3-phosphoglycerate kinase/lactate dehydrogenase reactions, decreased from the control value of 48.1 to 37.0 microM at 24 h after bile duct ligation. The maximal velocity (Vmax) of ATP synthesis, as measured by state 3 respiration of isolated mitochondria, decreased from the control value of 62.1 to 38.3 nmol ATP synthesized per min per mg mitochondrial protein, while the Michaelis constant for ADP (Km) decreased from the control value of 19.2 to 12.8 microM. ATP synthesis velocity in vivo }v: Vmax/[1 + (Km/[ADPf])], as calculated by Vmax, Km and ADPf, decreased from the control value of 44.4 to 28.5 nmol ATP synthesized per min per mg mitochondrial protein. Delta v/delta ADPf(delta v/delta ADPf: Vmax.Km/(Km + [ADPf])2), which indicates work-cost performance of the liver, decreased from the control value of 0.263 to 0.198. Biochemical output of the liver, as measured by hippurate synthesis from benzoate, decreased from the control value of 98.4 to 32.7 mg/h. These results indicate that synergistic decreases in ADPf, Vmax, v and delta v/delta ADPf take place in the course of deterioration of mitochondrial ATP synthesis and work output in jaundiced liver.

Changes in the distribution of the control of the mitochondrial oxidative phosphorylation in regenerating rabbit liver

Applying the metabolic control theory, inhibitor titration studies were carried out on Complex I, III, IV, ATP synthase, ATP/ADP carrier and P(i) carrier of mitochondrial oxidative phosphorylation in normal and regenerating rabbit liver in order to examine the acceleration mechanism of mitochondrial oxidative phosphorylation. In regenerating rabbit liver the rate of state 3 respiration, respiratory control ratio and phosphorylation rate in the presence of mM glutamate, 250 microM ADP and 3 mM inorganic phosphate increased significantly as compared with the control by 73%, 48% and 76%, respectively. The control of the rate of state 3 respiration in normal liver was exerted by Complexes I, IV and steps other than the aforementioned six steps, whose flux control coefficients were 0.317, 0.214 and 0.469, respectively. By contrast, in regenerating liver, the control was more evenly distributed among these steps in oxidative phosphorylation and the possibility is suggested that Complexes I, IV and steps other than the six steps are activated during regeneration. The activation of Complexes I and IV was attributed to their increased activity, since it was not accompanied by an increase in the amount of the enzymes.

Increased span of oxido-reduction states between pyridine nucleotide and cytochrome c oxidase in the regenerating rabbit liver as measured by arterial ketone body ratio and near-infrared spectroscopy

Oxido-reduction states of intramitochondrial pyridine nucleotide and cytochrome c oxidase and oxygen saturation of hemoglobin in the regenerating rabbit liver were studied with arterial ketone body ratio and tissue near-infrared spectroscopy. Arterial ketone body ratio (acetoacetate/beta-hydroxybutyrate), which reflects the oxido-reduction states of the intramitochondrial pyridine nucleotide (NAD+/NADH), was reduced from the control value of 0.93 +/- 0.09 to 0.42 +/- 0.03 12 h after 70% hepatectomy, while the oxido-reduction states of cytochrome c oxidase and the oxygen saturation of hemoglobin did not change. The velocity of ATP synthesis, as measured by state 3 respiration and ADP/O ratio in isolated mitochondria, increased by 61.4% 24 h after hepatectomy. These results support the near-equilibrium theory that an increased span in oxido-reduction state between pyridine nucleotide and cytochrome c oxidase drives mitochondrial ATP synthesis.

Quantitative detection of hemoglobin saturation in the liver with near-infrared spectroscopy

To quantify the changes in oxygen saturation of hemoglobin in the liver in hypoxia and liver transplantation, we applied a novel method using near-infrared spectroscopy. Instead of the conventional two-wave-length method, we obtained near-infrared data from a wide spectral range of 700 nm to 1,000 nm with continuous-wave spectroscopy. To correct the flattened spectral shape caused by photon scattering in living tissue, we then applied an equation taking into account the relationship between absorber concentration and actual absorption in scattering materials as assessed with time-resolved spectroscopy. Hepatic hemoglobin oxygen saturation was calculated with multicomponent analysis. In room air, hepatic hemoglobin oxygen saturation of rabbit was calculated as 57.4% +/- 2.5% (mean +/- S.E.M., n = 7). Arterial, portal and hepatic venous hemoglobin oxygen saturation were simultaneously measured as 97.5% +/- 0.7%, 77.1% +/- 3.4% and 55.5% +/- 4.6%, respectively. The changes in hepatic hemoglobin oxygen saturation seen in graded hypoxia were also close to those in hepatic venous hemoglobin oxygen saturation, suggesting that the average oxygenation state of sinusoidal blood approximates that in the central vein. We tested the clinical applicability of this method in a case of liver transplantation. It was determined that the hepatic hemoglobin oxygen saturation of the graft liver was heterogeneously distributed and that the initially low level of hepatic hemoglobin oxygen saturation was increased by the ligation of portal-systemic shunts.

The role of enhanced mitochondrial phosphorylation in rat liver transplantation

The effects of organ preservation on mitochondrial oxidative phosphorylation activity, adenylate hepatic energy charge, cytochrome content, and redox state of NAD+/NADH couple in rat liver transplantation were compared between a nonpreservation group and a preservation group with grafts preserved for 12 hr in Euro-Collin's solution. At 3 hr after transplantation, the energy charge in the preservation group decreased to 0.60 +/- 0.02 from the control value of 0.86 +/- 0.01, accompanied by a reduction of intramitochondrial redox state of NAD+/NADH couple. In contrast, in the nonpreservation group, the decrease in energy charge was minimally decreased to 0.79 +/- 0.04 due to the compensatory enhancement of mitochondrial oxidative phosphorylation activity. These results suggest that an enhanced mitochondrial ATP synthesis and a reduced intramitochondrial redox state are important factors affecting survival following rat liver transplantation.

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.