scholarly journals Metabolism of valine and 3-methyl-2-oxobutanoate by the isolated perfused rat kidney

1984 ◽  
Vol 224 (1) ◽  
pp. 109-116 ◽  
Author(s):  
R H Miller ◽  
A E Harper
Keyword(s):  
Amino Acids ◽  
High Activity ◽  
Rat Kidney ◽  
Linear Increase ◽  
Isolated Perfused Kidney ◽  
Isolated Perfused Rat Kidney ◽  
Acid Dehydrogenase ◽  
Perfused Rat Kidney ◽  
Branched Chain ◽  
Perfused Kidney

Metabolism of branched-chain amino and 2-oxo acids was studied in the isolated perfused kidney. Significant amounts of 2-oxo acids were released by perfused kidney with all concentrations of amino acids tested (0.1-1.0 mM each), despite the high activity of branched-chain 2-oxo acid dehydrogenase in kidney. As perfusate valine concentration was increased from 0.2 to 1.0 mM, [1-14C]valine transamination (2-oxo acid oxidized + released) increased roughly linearly; [1-14C]valine oxidation, however, increased exponentially. Increasing perfusate concentration of 3-methyl-2-oxo[1-14C]butanoate from 0 to 1.0 mM resulted in a linear increase in the rate of its oxidation and a rise in perfusate valine concentration; at the same time significant decreases occurred in perfusate isoleucine and leucine concentrations, with corresponding increases in rates of release of their respective 2-oxo acids. Comparison of rates of oxidation of [1-14C]valine and 3-methyl-2-oxo[1-14C]butanoate suggests that 2-oxo acid arising from [1-14C]valine transamination has freer access to the 2-oxo acid dehydrogenase than has the 2-oxo acid from the perfusate. The observations indicate that, when branched-chain amino and 2-oxo acids are present in perfusate at near-physiological concentrations, rates of transamination of the amino and 2-oxo acids by isolated perfused kidney are greater than rates of oxidation.

scholarly journals Metabolism of glycine- and hydroxyproline-containing peptides by the isolated perfused rat kidney

1985 ◽  
Vol 229 (2) ◽  
pp. 545-549 ◽  
Author(s):  
M Lowry ◽  
D E Hall ◽  
J T Brosnan
Keyword(s):  
Amino Acids ◽  
Rat Kidney ◽  
Isolated Perfused Rat Kidney ◽  
Perfused Rat Kidney ◽  
Rat Kidneys

Isolated perfused rat kidneys removed considerable quantities of glycyltyrosine, glycylhydroxyproline, tetraglycine and prolylhydroxyproline from the perfusate. The component amino acids are released into the perfusate and, in the case of the glycine-containing peptides, there is increased synthesis of serine. Removal of peptides was more than could be accounted for on the basis of filtration, so antiluminal metabolism is indicated. Metabolism of such peptides by the kidney may contribute to renal serine synthesis in vivo.

Transamination of branched-chain keto acids by isolated perfused rat kidney.

1978 ◽  
Vol 235 (1) ◽  
pp. E47
Author(s):  
W E Mitch ◽  
W Chan
Keyword(s):  
Amino Acids ◽  
Rat Kidney ◽  
Branched Chain Amino Acids ◽  
Keto Acid ◽  
Branched Chain Amino Acid ◽  
Keto Acids ◽  
Perfused Rat Kidney ◽  
Branched Chain ◽  
Branched Chain Keto Acids ◽  
Isolated Rat

Isolated rat kidney perfused without substrate released serine, glycine, and taurine, and substantially smaller amounts of other amino acids. When branched-chain keto acids were added, the corresponding amino acids were released at rates amounting to 15-25% of keto acid disappearance. Perfusion with 2 mM alpha-keto-isovalerate or alpha-keto-beta-methylvalerate caused an increased glucose release amounting to 18-23% of keto acid disappearance. The activity of branched-chain amino acid transferase (BATase) was significantly stimulated by perfusion with the analogue of leucine, but not by perfusion with alpha-ketoglutarate, the analogues of valine or isoleucine, or with leucine itself. These findings document that the kidney converts branched-chain keto acids in part to the corresponding amino acids and suggest that the keto analogue of leucine may be involved in the control of renal BATase activity, thereby indirectly regulating the metabolism of branched-chain amino acids.

scholarly journals Enhanced reabsorption of bicarbonate and phosphorus by the addition of amino acids in the isolated perfused rat kidney

1985 ◽  
Vol 27 (6) ◽  
pp. 951-953 ◽  
Author(s):  
Norihiko Terao ◽  
Muneya Suzuki ◽  
Yasushi Asano ◽  
Saichi Hosoda
Keyword(s):  
Amino Acids ◽  
Rat Kidney ◽  
Isolated Perfused Rat Kidney ◽  
Perfused Rat Kidney

scholarly journals Carbohydrate metabolism in the isolated perfused rat kidney

1972 ◽  
Vol 128 (2) ◽  
pp. 421-426 ◽  
Author(s):  
D. A. Hems ◽  
G. Gaja
Keyword(s):  
Carbohydrate Metabolism ◽  
Aerobic Glycolysis ◽  
Rat Kidney ◽  
Lactate Production ◽  
Anaerobic Conditions ◽  
Aerobic Conditions ◽  
Isolated Perfused Rat Kidney ◽  
Perfused Rat Kidney ◽  
Glycolytic Intermediates ◽  
Perfused Kidney

1. Anaerobic formation of lactate from glucose by isolated perfused rat kidney (411μmol/h per g dry wt.) was three times as fast as in aerobic conditions (138μmol/h per g). 2. In aerobic or in anaerobic conditions, the ratio of lactate production to glucose utilization was about 2. 3. Starvation or acidosis caused a decline of about 30% in the rate of aerobic glycolysis. 4. The rate of formation of glucose from lactate by perfused kidney from a well-fed rat, in the presence of 5mm-acetoacetate (83μmol/h per g dry wt.), was of the same order as the rate of aerobic glycolysis. 5. During perfusion with physiological concentrations of glucose (5mm) and lactate (2mm) there were negligible changes in the concentration of either substrate. 6. Comparison of kidneys perfused with lactate, from well-fed or starved rats, showed no major differences in contents of intermediates of gluconeogenesis. 7. The tissue concentrations of hexose monophosphates and C3 phosphorylated glycolytic intermediates (except triose phosphate) were decreased in anaerobic conditions. 8. Aerobic metabolism of fructose by perfused kidney was rapid: the rate of glucose formation was 726μmol/h per g dry wt. and of lactate formation 168μmol/h per g (dry wt.). Glycerol and d-glyceraldehyde were also released into the medium. 9. Aerobically, fructose generated high concentrations of glycolytic intermediates. 10. Anaerobic production of lactate from fructose (74μmol/h per g dry wt.) was slower than the aerobic rate. 11. In both anaerobic and aerobic conditions the ratio [lactate]/[pyruvate] in kidney or medium was lower during perfusion with fructose than with glucose. 12. These results are discussed in terms of the regulation of renal carbohydrate metabolism.

Stimulation of ammoniagenesis by acute acidosis: evidence for a urinary inhibitor

1980 ◽  
Vol 239 (5) ◽  
pp. F445-F451
Author(s):  
N. Terao ◽  
R. L. Tannen
Keyword(s):  
Metabolic Acidosis ◽  
Rat Kidney ◽  
Respiratory Acidosis ◽  
Urinary Ph ◽  
Isolated Perfused Kidney ◽  
Isolated Perfused Rat Kidney ◽  
Perfused Rat Kidney ◽  
Standard Collection ◽  
Acute Changes ◽  
Stimulation Of

To elucidate the factors mediating the response of renal ammoniagenesis to acute acidosis, the isolated perfused rat kidney was subjected to acute metabolic and respiratory acidosis with either standard collection or drainage of urine back into the perfusate. Midway during a 90-min perfusion with 0.4 mM glutamine and 5 mM glucose, perfusate pH was decreased to 6.8 by addition of HCl or alteration of the PCO2. Metabolic acidosis increased NH3 production, acidified the urine, and increased urinary NH4 excretion. Respiratory acidosis increased NH3 production to a comparable degree without urine acidification and with a minimal increase in NH4 excretion. When respiratory acidosis preceded perfusion at control PCO2 levels, NH3 production was increased but NH4 excretion was lower than control values. If urine drained back into the perfusate, NH3 production was not altered by either metabolic or respiratory acidosis. Accordingly, acute changes in perfusate pH stimulate renal ammoniagenesis by the isolated perfusate pH stimulate renal ammoniagenesis by the isolated perfused kidney independent of changes in urinary pH and NH4 excretion. This response is inhibited by an unidentified factor excreted in the urine.

Metabolism of arginine by the isolated perfused rat kidney

1978 ◽  
Vol 235 (4) ◽  
pp. F376-F380 ◽  
Author(s):  
G. O. Perez ◽  
M. Epstein ◽  
B. Rietberg ◽  
R. Loutzenhiser
Keyword(s):  
Amino Acids ◽  
Rat Kidney ◽  
Sprague Dawley ◽  
Bicarbonate Buffer ◽  
Net Production ◽  
Isolated Perfused Rat Kidney ◽  
Guanidine Derivatives ◽  
Sprague Dawley Rats ◽  
Perfused Rat Kidney ◽  
Guanidinosuccinic Acid

In order to evaluate the renal contribution to the metabolism of arginine, we have evaluated its biosynthesis and catabolism in the isolated perfused rat kidney. The kidneys of eight male Sprague-Dawley rats were perfused with Krebs-Ringer-bicarbonate buffer containing albumin and amino acids. Twenty-five muCi of L-[guanidino-14C]arginine or 25 muCi L-[guanidino-14C]citrulline were added to the system and radiochromatograms of the perfusate were obtained at 0, 30, 60, and 90 min. Perfusate levels of urea, creatine, and guanidine derivatives were measured with high-pressure liquid chromatography. During perfusion there was net utilization of arginine and net production of creatine, guanidinoacetic acid (GAA) and guanidinosuccinic acid (GSA). The guanidino carbon of arginine was incorporated by the kidney into urea, creatine GSA, GAA, and guanidinobutyric acid. The production of 14C-labeled urea from L-[guanidino-14C]citrulline was substantially lower than that previously demonstrated in the liver, while that of arginine was approximately 20 times greater. These studies demonstrate the important contribution of the kidney to the synthesis and metabolism of arginine.

Validation of a toxicity testing model by evaluating oxygen supply and energy state in the isolated perfused rat kidney

1991 ◽  
Vol 25 (3) ◽  
pp. 195-204 ◽  
Author(s):  
Takano Takehito ◽  
Nakata Kazuyo ◽  
Kawakami Tsuyoshi ◽  
Miyazaki Yoshifumi ◽  
Murakami Masataka ◽  
...  
Keyword(s):  
Oxygen Supply ◽  
Energy State ◽  
Rat Kidney ◽  
Toxicity Testing ◽  
Testing Model ◽  
Isolated Perfused Rat Kidney ◽  
Perfused Rat Kidney

Aldosterone Effects on Renal Function in the Isolated Perfused Rat Kidney

1979 ◽  
Vol 2 (1) ◽  
pp. 1-11
Author(s):  
Richard Solomon ◽  
Patricio Silva ◽  
Franklin H. Epstein
Keyword(s):  
Renal Function ◽  
Rat Kidney ◽  
Isolated Perfused Rat Kidney ◽  
Perfused Rat Kidney
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