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.

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 Effects of added adenine nucleotides on renal carbohydrate metabolism

1969 ◽  
Vol 115 (1) ◽  
pp. 1-10 ◽  
Author(s):  
M. J. Weidemann ◽  
D. A. Hems ◽  
H. A. Krebs
Keyword(s):  
Glucose Uptake ◽  
Carbohydrate Metabolism ◽  
Adenine Nucleotides ◽  
Rat Kidney ◽  
Kidney Cortex ◽  
Rat Kidney Cortex ◽  
Isolated Perfused Rat Kidney ◽  
Perfused Rat Kidney ◽  
Cortex Slices ◽  
Kidney Cortex Slices

1. The regulatory effects that adenine nucleotides are known to exert on enzymes of glycolysis and gluconeogenesis were demonstrated to operate in kidney-cortex slices and in the isolated perfused rat kidney by the addition of exogenous ATP, ADP and AMP to the incubation or perfusion media. 2. Both preparations rapidly converted added ATP into ADP and AMP, and ADP into AMP; added AMP was rapidly dephosphorylated. AMP formed from ATP was dephosphorylated at a lower rate than was added AMP, especially when the initial ATP concentration was high (10mm). Deamination of added AMP occurred more slowly than dephosphorylation of AMP. 3. Gluconeogenesis from lactate or propionate by rat kidney-cortex slices, and from lactate by the isolated perfused rat kidney, was inhibited by the addition of adenine nucleotides to the incubation or perfusion media. In contrast, oxygen consumption and the utilization of propionate or lactate by slices were not significantly affected by added ATP or AMP. 4. The extent and rapidity of onset of the inhibition of renal gluconeogenesis were proportional to the AMP concentration in the medium and the tissue, and were not due to the production of acid or Pi or the formation of complexes with Mg2+ ions. 5. Glucose uptake by kidney-cortex slices was stimulated 30–50% by added ATP, but the extra glucose removed was not oxidized to carbon dioxide and did not all appear as lactate. Glucose uptake, but not lactate production, by the isolated perfused kidney was also stimulated by the addition of ATP or AMP. 6. In the presence of either glucose or lactate, ATP and AMP greatly increased the concentrations of C3 phosphorylated intermediates and fructose 1,6-diphosphate in the kidney. There was a simultaneous rise in the concentration of malate and fall in the concentration of α-oxoglutarate. 7. The effects of added adenine nucleotides on renal carbohydrate metabolism seem to be mainly due to an increased concentration of intracellular AMP, which inhibits fructose diphosphatase and deinhibits phosphofructokinase. This conclusion is supported by the accumulation of intermediates of the glycolytic pathway between fructose diphosphate and pyruvate. 8. ATP or ADP (10mm) added to the medium perfusing an isolated rat kidney temporarily increased the renal vascular resistance, greatly diminishing the flow rate of perfusion medium for a period of several minutes.

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

EFFECTS OF CYCLOSPORINE ON THE ISOLATED PERFUSED RAT KIDNEY

1987 ◽  
Vol 43 (6) ◽  
pp. 795-799 ◽  
Author(s):  
David R. Luke ◽  
Bertram L. Kasiske ◽  
Gary R. Matzke ◽  
Walid M. Awni ◽  
William F. Keane
Keyword(s):  
Rat Kidney ◽  
Isolated Perfused Rat Kidney ◽  
Perfused Rat Kidney

METABOLISM OF RAM TESTICULAR SPERMATOZOA IN THE PRESENCE OF TESTOSTERONE AND RELATED STEROIDS

1970 ◽  
Vol 65 (3) ◽  
pp. 565-576 ◽  
Author(s):  
J. K. Voglmayr ◽  
R. N. Murdoch ◽  
I. G. White
Keyword(s):  
Aerobic Glycolysis ◽  
Rete Testis ◽  
Glycolytic Metabolism ◽  
Anaerobic Conditions ◽  
Aerobic Conditions ◽  
Testicular Spermatozoa ◽  
Almost All ◽  
Oxidation Of Glucose

ABSTRACT The effects of testosterone* and related steroids on the oxidative and glycolytic metabolism of freshly collected ram testicular spermatozoa and of spermatozoa stored under air in rete testis fluid for 3 days at 3°C have been studied. When freshly collected testicular spermatozoa were incubated with glucose under aerobic conditions only a small proportion of the utilized glucose could be accounted for as lactate. The addition of a number of steroids, including testosterone, androstanedione, 5β-androstanedione, androsterone, epiandrosterone and 5β-androsterone, greatly increased aerobic glycolysis, the oxidation of the substrate and the proportion of the utilized substrate converted to lactic acid. After 3 days storage at 3°C, testicular spermatozoa respired at a greater rate than spermatozoa freshly collected from the testes. Although the stimulating effect of steroids on aerobic glycolysis increased after storage, they depressed rather than stimulated the oxidation of glucose by stored testicular spermatozoa. With the exception of androstanedione, which slightly stimulated glycolysis, storage of testicular spermatozoa for 3 days in the presence of steroids did not significantly influence their subsequent metabolism when washed free of the steroids. Both freshly collected and stored ram testicular spermatozoa displayed a marked Pasteur effect, and utilized more glucose and produced more lactate under anaerobic than under aerobic conditions. In the absence of oxygen the steroids did not stimulate glycolysis to any extent. However, epiandrosterone depressed the glycolysis of freshly collected spermatozoa under anaerobic conditions and after storage, 5β-androsterone had a similar effect. Androstanedione, 5β-androstanedione, epiandrosterone and 5β-androsterone were the most effective steroids in altering the metabolism of testicular spermatozoa and, under almost all conditions of incubation, depressed the synthesis of amino acids from glucose. The results suggest that the effects of testosterone and related steroids in vitro may depend on the age of the spermatozoa after their release from the Sertoli cells; the steroid effects may have important consequences in vivo in relation to sperm maturation.

Comparison of the effects of parathyroid hormone (PTH) and recombinant PTH-related protein on bicarbonate excretion by the isolated perfused rat kidney

1990 ◽  
Vol 126 (3) ◽  
pp. 403-408 ◽  
Author(s):  
A. G. Ellis ◽  
W. R. Adam ◽  
T. J. Martin
Keyword(s):  
Parathyroid Hormone ◽  
Rat Kidney ◽  
Urine Volume ◽  
Clinical Manifestations ◽  
Fractional Excretion ◽  
Bicarbonate Concentration ◽  
Isolated Perfused Rat Kidney ◽  
Amino Terminal ◽  
Fractional Excretion Of Sodium ◽  
Perfused Rat Kidney

ABSTRACT The isolated perfused rat kidney was used to study the effects of amino-terminal fragments of human parathyroid hormone, hPTH(1–34), bovine parathyroid hormone, bPTH(1–84) and of PTH-related proteins, PTHrP(1–34), PTHrP(1–84), PTHrP(1–108) and PTHrP(1–141) on urinary bicarbonate excretion. PTHrP(1–34) (7 nmol/l), bPTH(1–84) (5·5 nmol/l) and hPTH(1–34) (7 nmol/l) had similar effects in increasing bicarbonate excretion with respect to the control. At lower concentrations (0·7 nmol/l) all PTHrP components, but not hPTH(1–34) or bPTH(1–84) increased bicarbonate excretion significantly. Infusions of PTHrP(1–108) and PTHrP(1–141) at 0·7 nmol/l, while associated with a rise in urinary bicarbonate concentration and excretion during the early stages of perfusion, produced a sharp decline in bicarbonate concentration and excretion in the latter part of perfusion. The different peptides produced no significant differences in glomerular filtration rate, fractional excretion of sodium or urine volume. The absence of substantial differences between the effects of hPTH(1–34) and PTHrP(1–34) are as noted in previous studies. The differences between PTHrP(1–108)/PTHrP(1–141) and PTHrP(1–34) demonstrated here are consistent with (1) the clinical manifestations of acidosis in hyperparathyroidism and alkalosis in humoral hypercalcaemia of malignancy, and (2) an independent action of a component of PTHrP beyond amino acids 1–34. Journal of Endocrinology (1990) 126, 403–408

Sign in / Sign up

Export Citation Format

Share Document