scholarly journals Biochemical effects of the hypoglycaemic compound pent-4-enoic acid and related non-hypoglycaemic fatty acids. Carbohydrate metabolism

1968 ◽  
Vol 110 (3) ◽  
pp. 521-527 ◽  
Author(s):  
A. E. Senior ◽  
H. S. A. Sherratt
Keyword(s):  
Rat Liver ◽  
Rat Kidney ◽  
Enoic Acid ◽  
Rat Tissues ◽  
Pentanoic Acid ◽  
Kidney Slices ◽  
Biochemical Effects ◽  
Low Concentrations ◽  
Cyclopropanecarboxylic Acid ◽  
Cyclobutanecarboxylic Acid

1. The effects of the hypoglycaemic compound, pent-4-enoic acid, and of four structurally related non-hypoglycaemic compounds (pent-2-enoic acid, pentanoic acid, cyclopropanecarboxylic acid and cyclobutanecarboxylic acid), on glycolysis, glucose oxidation and gluconeogenesis in some rat tissues were determined. 2. None of the compounds at low concentrations inhibited glycolysis by particle-free supernatant fractions from rat liver, skeletal muscle and intestinal mucosa, though there was inhibition by cyclopropanecarboxylic acid and cyclobutanecarboxylic acid at 3mm concentration. 3. Pent-4-enoic inhibited the oxidation of [1−14C]palmitate by rat liver slices, but did not increase the oxidation of [U−14C]glucose. 4. Pent-4-enoic acid (0·01mm) strongly inhibited gluconeogenesis by rat kidney slices from pyruvate or succinate, but none of the other compounds inhibited significantly at low concentrations. 5. There was also some inhibition of gluconeogenesis in kidney slices from rats injected with pent-4-enoic acid. 6. The mechanism of the hypoglycaemic effect of pent-4-enoic acid is discussed; it is suggested that there is an inhibition of fatty acid and ketone-body oxidation and of gluconeogenesis so that glucose reserves become exhausted, leading to hypoglycaemia. 7. The mechanism of the hypoglycaemic action of pent-4-enoic acid appears to be similar to that of hypoglycin.

scholarly journals Biochemical effects of the hypoglycaemic compound pent-4-enoic acid and related non-hypoglycaemic fatty acids. Oxidative phosphorylation and mitochondrial oxidation of pyruvate, 3-hydroxybutyrate and tricarboxylic acid-cycle intermediates

1968 ◽  
Vol 110 (3) ◽  
pp. 499-509 ◽  
Author(s):  
A. E. Senior ◽  
H. S. A. Sherratt
Keyword(s):  
Oxidative Phosphorylation ◽  
Tricarboxylic Acid Cycle ◽  
Time Lag ◽  
Liver Mitochondria ◽  
Enoic Acid ◽  
Rat Liver Mitochondria ◽  
Pentanoic Acid ◽  
Low Concentrations ◽  
Cyclobutanecarboxylic Acid ◽  
Tricarboxylic Acid Cycle Intermediates

1. The effects of the hypoglycaemic compound pent-4-enoic acid, and of four structurally related non-hypoglycaemic compounds (pent-2-enoic acid, pentanoic acid, cyclopropanecarboxylic acid and cyclobutanecarboxylic acid), on several reactions in rat liver mitochondria were determined. 2. The use of manometric techniques for measurements of oxidations and of phosphorylation is critically discussed. 3. Pent-4-enoic acid and pentanoic acid uncoupled oxidative phosphorylation at low concentrations, but usually by not more than about 50%. 4. All the compounds, except cyclobutanecarboxylic acid, strongly inhibited the oxidation of pyruvate and 2-oxoglutarate, but the oxidations of succinate, citrate and 3-hydroxybutyrate were not strongly inhibited. 5. All the compounds, except cyclobutanecarboxylic acid, inhibited decarboxylation of [1−14C]pyruvate with ferricyanide as electron acceptor. 6. All the compounds, except pent-2-enoic acid, caused mitochondrial swelling after a time-lag.

scholarly journals N 6-Trimethyl-lysine metabolism. 3-Hydroxy-N6-trimethyl-lysine and carnitine biosynthesis

1980 ◽  
Vol 188 (2) ◽  
pp. 509-519 ◽  
Author(s):  
C L Hoppel ◽  
R A Cox ◽  
R F Novak
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Rat Liver ◽  
Rat Kidney ◽  
Major Metabolite ◽  
Kidney Slices ◽  
Liver And Kidney ◽  
Nuclear Magnetic Resonance Spectrometry ◽  
Magnetic Resonance Spectrometry ◽  
Lysine Metabolism

Rats injected with N6-[Me-3H]trimethyl-lysine excrete in the urine five radioactively labelled metabolites. Two of these identified metabolites are carnitine and 4-trimethylammoniobutyrate. A third metabolite, identified as 5-trimethylammoniopentanoate, is not an intermediate in the biosynthesis of carnitine; the fourth and major metabolite, N2-acetyl-N6-trimethyl-lysine, is not a precursor of carnitine. The remaining metabolite (3-hydroxy-N6-trimethyl-lysine) is converted into trimethylammoniobutyrate and carnitine by rat liver slices and into trimethylammoniobutyrate by rat kidney slices. In rat liver and kidney-slice experiments, radioactivity from DL-N6-trimethyl-[1-14C]lysine and DL-N6-trimethyl-[2-14C]lysine was incorporated into N2-acetyl-N6-trimethyl-lysine and 3-hydroxy-N6-trimethyl-lysine, but not into trimethylammoniobutyrate or carnitine. A procedure was devised to purify milligram quantities of 3-hydroxy-N6-trimethyl-lysine from the urine of rats injected chronically with N6-trimethyl-lysine (100 mg/kg body wt. per day). The structure of 3-hydroxy-N6-trimethyl-lysine was confirmed chemically and by nuclear-magnetic-resonance spectrometry [Novak, Swift & Hoppel (1980) Biochem. J. 188, 521–527]. The sequence for carnitine biosynthesis in liver is: N6-trimethyl-lysine leads to 3-hydryxy-N6-trimethyl-lysine leads to leads to 4-trimethylammoniobutyrate leads to carnitine.

scholarly journals Purification and properties of arginase of rat kidney

1973 ◽  
Vol 133 (4) ◽  
pp. 779-788 ◽  
Author(s):  
George A. Kaysen ◽  
Harold J. Strecker
Keyword(s):  
Rat Liver ◽  
Rat Kidney ◽  
Mitochondrial Fraction ◽  
Tissue Extracts ◽  
Low Concentrations ◽  
Purification And Properties ◽  
Hydrolysis Rates ◽  
Kidney Enzyme ◽  
Acetone Treatment ◽  
Unknown Factor

l-Arginase from rat kidney was partially purified and some properties were compared with those of l-arginase of rat liver. The kidney enzyme was firmly bound to the mitochondrial fraction and after solubilization required arginine or an unknown factor in tissue extracts for stabilization after dialysis. The two enzymes differed also in stability with respect to acetone treatment, heating or freezing. In further contrast with liver arginase, arginase from kidney was not adsorbed to CM-cellulose at pH7.5 and its activity was not increased by incubation with Mn2+. Other differences were seen in relative specificities for substrates, ratio of hydrolysis rates with high and low concentrations of arginine and effects of certain inhibitors. Antisera prepared to pure liver arginase did not cross-react with partially purified kidney arginase.

Azotaemic Inhibition of Organic Anion Transport in the Kidney of the Rat: Mechanisms and Characteristics

1971 ◽  
Vol 40 (2) ◽  
pp. 159-169 ◽  
Author(s):  
E. P. Orringer ◽  
F. R. Weiss ◽  
H. G. Preuss
Keyword(s):  
Rat Kidney ◽  
Organic Anion ◽  
Anion Transport ◽  
Renal Transport ◽  
Organic Anion Transport ◽  
Kidney Slices ◽  
Low Concentrations ◽  
The Media ◽  
High Concentrations

1. While azotaemic sera depressed the in-vitro Na-iodohippurate transport of rat kidney slices at any concentration, normal sera excited transport at low concentrations and depressed transport at high concentrations. The depression of transport by azotaemic sera was partially overcome by neomycin feeding in contrast to the depression by normal sera, which was not altered by neomycin feeding. 2. Plotting the reciprocal of sodium-iodohippurate accumulated by slices against the reciprocal of the media concentrations of sodium iodohippurate suggested that the depression of hippurate transport produced by normal and azotaemic sera was competitive in nature. 3. Normal sera slowed the efflux of Na-iodohippurate from kidney slices while azotaemic sera affected it very little. 4. The depression produced by normal and azotaemic sera and the stimulation produced by low concentrations of normal sera were seen with serum ultrafiltrates and dialysates, and after passage through cation exchange columns, but not anion exchange columns. 5. The effects on Na-iodohippurate accumulation by normal and azotaemic sera could be reproduced with metabolizable (lactate), and nonmetabolizable (hippurate) organic anions as well as combinations of these. 6. The implications of these observations on the altered renal transport of Na-iodohippurate produced by azotaemic and normal sera are discussed.

scholarly journals Ouabain-insensitive, Na+-stimulated ATPase of several rat tissues: activity during a 24 h period

2009 ◽  
pp. 693-699
Author(s):  
A Reyes ◽  
MM Galindo ◽  
L García ◽  
D Segura-Peña ◽  
C Caruso-Neves ◽  
...  
Keyword(s):  
Atpase Activity ◽  
Blood Plasma ◽  
Rat Kidney ◽  
Kidney Cortex ◽  
Rat Tissues ◽  
Na Transport ◽  
Rat Kidney Cortex ◽  
Low Concentrations ◽  
Two Peaks ◽  
Daily Changes

Rhythmic daily changes in the Na,K-ATPase activity have been previously described for rat kidney cortex, showing two peaks: at 0900 h and 2100 h, and two valleys: at 1500 h and 0100 h - 0300 h. The oscillations in Na,K-ATPase activity are produced by an inhibitor, which binds the enzyme and is present in the rat blood plasma at valley times and absent or at very low concentrations at peak times. Since it has been demonstrated that active Na+ extrusion from the cells of several tissues depends not only on the Na,K-ATPase but also on the ouabaininsensitive Na-ATPase, we studied the activity of this latter enzyme of several rat tissues, i.e., kidney cortex, small intestine, liver, heart and red blood cells along the day. None of these tissues showed any variation of their Na-ATPase activity along the day. Preincubation of kidney cortex homogenates obtained at 0900 h, with blood plasma drawn at 0900 h and 1500 h, did not modify the Na-ATPase activity. Our results indicate that the NaATPase activity does not oscillate along the day. These results are in agreement with the idea that the Na-ATPase could partially compensate the Na+ transport affected by oscillations of the Na,K-ATPase activity.

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.

Studies of calcium-45 desaturation from kidney slices in flow-through chambers

1978 ◽  
Vol 234 (1) ◽  
pp. R34-R38
Author(s):  
T. Uchikawa ◽  
A. B. Borle
Keyword(s):  
Kinetic Parameters ◽  
Rat Kidney ◽  
Kidney Cells ◽  
Tissue Slices ◽  
Kidney Slices ◽  
System A ◽  
Order Of Magnitude ◽  
Exponential Equations ◽  
Flow Through ◽  
Best Fit

This paper describes a method to measure calcium fluxes and calcium exchangeable pools in tissue slices by continuous perifusion in flow-through chambers. 45Ca desaturation from rat kidney slices can be analyzed as in an open three-compartment catenary system. A set of equations is given to calculate all the relevant kinetic parameters from the triple exponential equations which best fit the desaturation curves. The results show that the kinetic parameters obtained in kidney slices by this new method are in the same order of magnitude as those previously observed in cultured monkey kidney cells.

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