Comparative activity and intracellular distribution of tricarboxylic acid cycle enzymes in Haemonchus contortus larvae and rat liver

1967 ◽  
Vol 23 (2) ◽  
pp. 335-359 ◽  
Author(s):  
C.W Ward ◽  
P.J Schofield
1968 ◽  
Vol 110 (2) ◽  
pp. 313-335 ◽  
Author(s):  
D. F. Heath

A scheme is presented that shows how the reactions involved in gluconeogenesis, glycolysis and the tricarboxylic acid cycle are linked in rat liver. Equations are developed that show how label is redistributed in aspartate, glutamate and phosphopyruvate when it is introduced as specifically labelled pyruvate or glucose either at a constant rate (steady-state theory) or at a variable rate (non-steady-state theory). For steady-state theory the fractions of label introduced as specifically labelled pyruvate that are incorporated into glucose and carbon dioxide are also given, and for both theories the specific radioactivities of aspartate and glutamate relative to the specific radioactivity of the substrate. The theories allow for entry of label into the tricarboxylic acid cycle via both oxaloacetate and acetyl-CoA, for 14CO2 fixation and for loss of label from the tricarboxylic acid cycle in glutamate, but not for losses in citrate. They also allow for incomplete symmetrization of label in oxaloacetate due to incomplete equilibration with fumarate both in the extramitochondrial part of the cell and in the mitochondrion on entry of oxaloacetate into the tricarboxylic acid cycle. In the latter case failure both of oxaloacetate to equilibrate with malate and of malate to equilibrate with fumarate are considered.


1965 ◽  
Vol 43 (3) ◽  
pp. 359-372 ◽  
Author(s):  
E. R. Tustanoff ◽  
H. B. Stewart

In a previous paper it was shown that neutral salt or sucrose, probably as a consequence of osmotic activity, interferes with the utilization of pyruvate by washed particle preparations from rat liver. In the present paper the effects of neutral salt on reaction sequences in the tricarboxylic acid cycle have been investigated. α-Oxoglutarate utilization is inhibited by salt in a fashion that closely resembles the osmolar inhibition of pyruvate oxidation. Citrate, but not cis-aconitate or isocitrate, utilization is inhibited by salt concentrations somewhat greater than those required for inhibition of α-oxo acid metabolism. Succinate, fumarate, and malate utilization are not highly sensitive to salt inhibition, and anaerobic utilization of citrate in the presence of 1,10-phenanthroline does not appear to be affected by salt.


1999 ◽  
Vol 20 (4) ◽  
pp. 292-302 ◽  
Author(s):  
David M. Yarmush ◽  
Annette D. MacDonald ◽  
Brent D. Foy ◽  
Francois Berthiaume ◽  
Ronald G. Tompkins ◽  
...  

1986 ◽  
Vol 233 (2) ◽  
pp. 321-324 ◽  
Author(s):  
W M Taylor ◽  
E van de Pol ◽  
F L Bygrave

Output of 14CO2 from 1-14C-labelled glutamate, 2-oxoglutarate or octanoate and from 4-methyl-2-oxo[2-14C]pentanoate was increased by more than 100% after infusion of phenylephrine into perfused livers of fed rats. Infusion of ethanol or sorbitol raised 3-hydroxybutyrate/acetoacetate ratios and decreased the output of 14CO2. Increases in 14CO2 output induced by phenylephrine were observed in the presence or absence of ethanol or sorbitol and were accompanied by elevated 3-hydroxybutyrate/acetoacetate ratios under all conditions examined. Phenylephrine had no effect on total tissue ATP/ADP ratios in livers from fed or starved rats. The data suggest that phenylephrine-induced increases in tricarboxylic acid-cycle flux do not arise from lowered matrix NADH/NAD+ or ATP/ADP ratios.


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