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K R Elliott

Publications and source records attributed to K R Elliott.

47 records · Page 3Linked to original sources
PubMed1977

Preparation and characterization of isolated parenchymal cells from guinea pig liver.

1. A method is described for the preparation of isolated cells from guinea pig liver. This involved perfusion in situ, in the non-physiological direction, with collagenase. 2. The cell yield was 20--30%, comparable with those from the livers of other species. 3. The ratio of lactate dehydrogenase to glutamate dehydrogenase in the cells was similar to that in vivo, indicating that there was negligible leakage of cytoplasmic enzymes. 4. The concentrations of K+ and adenine nucleotides were initially lower than in the perfused liver; normal values were obtained on incubation, particularly in the presence of substrate. 5. The L-lactate: pyruvate ratio is 16:1, close to established values. The total beta-hydroxybutyrate: acetoacetate ratio indicates that the mitochondrial redox state is more oxidised than in the perfused liver, but the intracellular ratio is similar to that of the intact liver. 6. Rates of gluconeogenesis and ureogenesis, are within the physiological range. Maximal gluconeogeneis from L-lactate was preceded by a lag period. L-lysine stimulated glucose production from L-lactate but did not abolish the lag phase. 7. The effects of aminooxyacetate and octanoate on L-lactate gluconeogenesis were similar to those in the perfused liver.

Adenine Nucleotides↗
PubMed1977

The effects of starvation and experimental diabetes on phosphoenol-pyruvate carboxykinase in the guinea pig.

1. Approx. 85% of liver phosphoenolpyruvate carboxykinase is associated with the mitochondrial fraction in the fed guinea pig. Enzyme activity is unchanged in diabetes, but doubles during starvation. In contrast with earlier reports, both cytoplasmic and mitochondrial activities were found to be increased. 2. In kidney cortex, total enzyme activity is increased in both starved and diabetic animals. These changes are associated with increases in the cytoplasmic activity alone. 3. In diabetic animals the mean blood-glucose concentration was 23.1 mM. Other blood metabolites were lower than those in the rat, and the animals did not show significant ketosis. 4. Changes in the rates of gluconeogenesis from lactate and propionate paralleled those in phosphoenolpyruvate carboxykinase activity.

Animals↗
PubMed1977

Permeability of the liver cell membrane to quinolinate.

Quinolinate was taken up by both rat and guinea-pig liver cells. Equilibrium was reached after approx. 20 min with rat cells, but guinea-pig cells had not achieved a steady state after 60 min. There was no evidence to suggest that quinolinate is rapidly metabolized by either species. The concentrations of quinolinate attained in rat and guinea-pig cells after short periods of incubation with 0.5 mM-quinolinate did not inhibit gluconeogenesis. These results raise further doubts as to the mechanism of quinolinate action in liver.

Animals↗
PubMed1974

A kinetic analysis of enzyme systems involving four substrates.

A treatment of kinetic data for enzyme mechanisms involving four substrates is described. The initial-rate equations and product-inhibition patterns for such mechanisms are presented. The treatment is extended to include analysis of enzyme mechanisms involving three substrates in which two molecules of one substrate are used.

Enzymes↗
PubMed1974

Kinetic studies of bovine liver carbamoyl phosphate synthetase.

A through study of initial-rate data has been made on carbamoyl phosphate synthetase from bovine liver. On the basis of the results the order of substrate binding to the enzyme is ATPMg followed by HCO(3) (-), ATPMg and NH(4) (+). A model for the enzymic mechanism is proposed, and the rate equations describing it are presented. Details of the derivation of the initial-rate equation for the kinetic mechanism proposed have been deposited as Supplementary Publication SUP 50032 (6 pages) at the British Library, Lending Division (formerly the National Lending Library for Science and Technology), Boston Spa, Yorks. LS23 7QB, U.K., from whom copies may be obtained on the terms indicated in Biochem. J. (1973), 131, 5.

Adenosine Triphosphate↗
PubMed1974

Product inhibition studies on bovine liver carbamoyl phosphate synthetase.

A study of the product-inhibition patterns of carbamoyl phosphate synthetase from bovine liver is reported. Inhibition by adenosine, AMP and inorganic ions is also reported. The results are in agreement with the previously proposed model in which the order of substrate binding is ATPMg, followed by HCO(3) (-), ATPMg and NH(4) (+). The order of product release on the basis of the reported results is carbamoyl phosphate, followed by ADPMg, ADPMg and inorganic phosphate.

Adenosine↗