scholarly journals The redox state of the nicotinamide–adenine dinucleotides in rat liver homogenates

1968 ◽  
Vol 108 (4) ◽  
pp. 513-520 ◽  
Author(s):  
H. A. Krebs ◽  
T. Gascoyne
Keyword(s):  
Rat Liver ◽  
Redox State ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Redox States ◽  
Cell Compartments ◽  
Dehydrogenase System ◽  
Liver Homogenates ◽  
Saline Medium ◽  
Pyruvate Ratio

1. The redox state of the NAD couple of rat liver mitochondria, as measured by the [β-hydroxybutyrate]/[acetoacetate] ratio, rapidly changed in the direction of oxidation during the preparation of homogenates in a saline medium. The value of the [β-hydroxybutyrate]/[acetoacetate] ratio fell from 2·3 to 0·15 in 10min. EDTA diminished the fall and succinate prevented it. 2. The redox state of the rat liver cytoplasm, as measured by the [lactate]/[pyruvate] ratio, changed slightly in the direction of reduction during the preparation of homogenate. This was prevented by succinate. 3. In unsupplemented homogenates the differences in the redox states of mitochondria and cytoplasm decreased. Succinate and EDTA together maintained the differences within the physiological range. A measure of the ability of the mitochondria to maintain different redox states in mitochondria and cytoplasm is the value of the expression [lactate][acetoacetate]/[pyruvate][β-hydroxybutyrate]. If there are no differences in the redox states of the NAD in the two cell compartments the value of the expression is 444 at 37°. The value in the intact rat liver is between 4·7 and 21. 4. α-Oxoglutarate or glutamate were still more effective than succinate in maintaining high [β-hydroxybutyrate]/[acetoacetate] ratios in the homogenates because these substrates supply a reducing agent of NAD+ and, through succinate, an inhibitor of the oxidation of NADH. 5. When supplemented with α-oxoglutarate and EDTA, homogenates readily adjust the redox state of the β-hydroxybutyrate dehydrogenase system after it has been upset by the addition of either acetoacetate or β-hydroxybutyrate. 6. Amytal and rotenone raised the value of the [β-hydroxybutyrate]/[acetoacetate] ratio. This is taken to indicate that the reduction of acetoacetate in the homogenates was not an energy-linked process. 7. 2,4-Dinitrophenol shifted the [β-hydroxybutyrate]/[acetoacetate] ratio in the presence of succinate in favour of oxidation because it inhibited the oxidation of succinate and accelerated the oxidation of NADH. 8. Rotenone increased the rate of ketone-body formation of liver homogenates, though it decreased the rate of oxygen uptake.

Differences in cholesterol oxidation and biosynthesis in liver of male and female rats

1961 ◽  
Vol 200 (3) ◽  
pp. 519-522 ◽  
Author(s):  
David Kritchevsky ◽  
Ezra Staple ◽  
Joseph L. Rabinowitz ◽  
Michael W. Whitehouse
Keyword(s):  
Rat Liver ◽  
Sodium Acetate ◽  
Liver Mitochondria ◽  
Female Rats ◽  
Male Rats ◽  
Cholesterol Oxidation ◽  
Male Rat ◽  
Rat Liver Mitochondria ◽  
Oxidized Cholesterol ◽  
Liver Homogenates

Female rat liver mitochondria oxidized cholesterol-26-C14 and sodium pyruvate-2-C14 to C14O2 to a much greater extent (per mg N) than did male rat liver mitochondria. Mitochondrial preparations from livers of castrated, estrogenized or castrated-estrogenized male rats all oxidized cholesterol-26-C14 to a greater extent than did liver preparations from normal male rats. No differences were observed in the oxidation of sodium octanoate-1-C14. The serum and liver cholesterol levels of the feminized rats were higher than those of the intact males. Biosynthesis of cholesterol from sodium acetate-2-C14 by male rat liver homogenates was significantly lower than biosynthesis by liver homogenates from normal female rats or gonadectomized rats of both sexes. The rate of biosynthesis from mevalonic acid-2-C14 by liver homogenates from castrated male rats was much higher than in homogenates of oophorectomized females or intact males or females. Differences in sex or gonadectomy had no effect on biosynthesis of fatty acids from sodium acetate-2-C14.

Effects of 5-5'-Diphenyl-2-thiohydantoin (DPTH) and Thyroxine on the Ultrastructure and Chemical Composition of Rat Liver

1971 ◽  
Vol 29 ◽  
pp. 570-571
Author(s):  
E. A. Elfont ◽  
R. B. Tobin ◽  
D. G. Colton ◽  
M. A. Mehlman
Keyword(s):  
Chemical Composition ◽  
Rat Liver ◽  
Future Study ◽  
Mode Of Action ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Effective Inhibitor ◽  
Biochemical Effects ◽  
Glycerophosphate Dehydrogenase ◽  
Stimulation Of

Summary5,-5'-diphenyl-2-thiohydantoin (DPTH) is an effective inhibitor of thyroxine (T4) stimulation of α-glycerophosphate dehydrogenase in rat liver mitochondria. Because this finding indicated a possible tool for future study of the mode of action of thyroxine, the ultrastructural and biochemical effects of DPTH and/or thyroxine on rat liver mere investigated.Rats were fed either standard or DPTH (0.06%) diet for 30 days before T4 (250 ug/kg/day) was injected. Injection of T4 occurred daily for 10 days prior to sacrifice. After removal of the liver and kidneys, part of the tissue was frozen at -50°C for later biocheailcal analyses, while the rest was prefixed in buffered 3.5X glutaraldehyde (390 mOs) and post-fixed in buffered 1Z OsO4 (376 mOs). Tissues were embedded in Araldlte 502 and the sections examined in a Zeiss EM 9S.Hepatocytes from hyperthyroid rats (Fig. 2) demonstrated enlarged and more numerous mitochondria than those of controls (Fig. 1). Glycogen was almost totally absent from the cytoplasm of the T4-treated rats.

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