Pyruvate dehydrogenase and the regulation of glucose metabolism in ruminant tissues

Robertson, James P.; Faulkner, Anne; Vernon, Richard G.

doi:10.1016/0014-5793(80)80295-x

Cited by 15 publications

(8 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The higher rates of fatty acid synthesis from glucose observed after tissue culture are associated with a higher pyruvate concentration, and incubation of the tissue with 4 mM-L-lactate, which is likely to increase the intracellular pyruvate concentration, resulted in a higher flux of carbon to fatty acids than was observed with glucose. These observations are consistent with our previous suggestion that pyruvate dehydrogenase has an important role in limiting the further metabolism of glucose in sheep adipose tissue (Robertson et al, 1980) as previously shown for rat adipose tissue (see Denton, 1975;Randle, 1978).…”

Section: Discussionsupporting

confidence: 93%

“…The low activities of pyruvate dehydrogenase and of fatty acid, ATP citrate lyase are in agreement with previous thesis, although reports (see Vernon, 1980;Robertson et al, 1980).…”

Section: Discussionsupporting

confidence: 92%

“…Pyruvate dehydrogenase was assayed as described previously (Robertson et al, 1980). except that pyruvate and Mg2+ concentrations of the assay medium were increased to 3 mm and 2 mm respectively and 6 mM-pyruvate was added during the activation step.…”

Section: Measurement Ofenzyme Activitiesmentioning

confidence: 99%

See 2 more Smart Citations

Regulation of glycolysis and fatty acid synthesis from glucose in sheep adipose tissue

Robertson

Faulkner

Vernon

1982

Biochemical Journal

Self Cite

View full text Add to dashboard Cite

1. The following were measured in adipose-tissue pieces, obtained from 7-9 month-old sheep, before or after the tissue pieces had been maintained in tissue culture for 24 h: the rates of synthesis from glucose of fatty acids, acylglycerol glycerol, pyruvate and lactate; the rate of glucose oxidation to CO(2); the rate of glucose oxidation via the pentose phosphate pathway; the activities of hexokinase, glucose 6-phosphate dehydrogenase, phosphofructokinase, pyruvate kinase, pyruvate dehydrogenase and ATP citrate lyase; the intra- and extra-cellular water content; the concentration of various metabolites and ATP, ADP and AMP. 2. The proportion of glucose carbon converted into the various products in sheep adipose tissue differs markedly from that observed in rat adipose tissue. 3. There was a general increase in the rate of glucose utilization by the adipose-tissue pieces after maintenance in tissue culture; largest changes were seen in the rates of glycolysis and fatty acid synthesis from glucose. These increases are paralleled by an increase in pyruvate kinase activity. There was no change in the activities of the other enzymes as measured, although the net flux through all the enzymes increased. 4. Incubation of fresh adipose-tissue pieces for 2-6h led to an increase in the affinity of pyruvate kinase for phosphoenolpyruvate. 5. The rate of pyruvate production by glycolysis was greater than the activity of pyruvate dehydrogenase of the tissue. 6. The results suggest that both pyruvate kinase and pyruvate dehydrogenase have important roles in restricting the utilization of glucose carbon for fatty acid synthesis in sheep adipose tissue.

show abstract

Section: Discussionsupporting

confidence: 93%

“…The low activities of pyruvate dehydrogenase and of fatty acid, ATP citrate lyase are in agreement with previous thesis, although reports (see Vernon, 1980;Robertson et al, 1980).…”

Section: Discussionsupporting

confidence: 92%

See 1 more Smart Citation

Regulation of glycolysis and fatty acid synthesis from glucose in sheep adipose tissue

Robertson

Faulkner

Vernon

1982

Biochemical Journal

Self Cite

View full text Add to dashboard Cite

show abstract

“…Investigations of lipogenesis or glucose metabolism in ruminant adipose tissues typi cally have involved the utilization of tissues from either sheep (1)(2)(3)(4)(5) or cattle (6)(7)(8)(9)(10)(11)(12)(13)(14), but seldom both. While numerous metabolic similarities exist between ovine and bovine adipose tissues, enough conflicting results have been obtained to cast doubt on the wis dom of extending the results based on studies from one ruminant species to ruminants in general.…”

mentioning

confidence: 99%

Comparisons of Lipogenesis and Glucose Metabolism between Ovine and Bovine Adipose Tissues

Smith

Prior

1986

The Journal of Nutrition

View full text Add to dashboard Cite

Studies were initiated to compare glucose and lipid metabolism in vitro in subcutaneous adipose tissue of mature sheep and cattle. Mean adipocyte volume was significantly less in subcutaneous adipose tissue of sheep than in adipose tissue from cattle. The presence of acetate and lactate in the incubation medium increased total glucose utilization two- to three-fold in ovine adipose tissue, but had no effect on total glucose utilization in adipose tissue from cattle. Acetate provided 72-82% of the acetyl units to lipogenesis, depending on species and substrate concentration. There were no significant (P greater than 0.05) differences in the contribution of the pentose cycle to the provision of reducing equivalents to fatty acid biosynthesis, based on the incorporation of label from [3-3H]glucose into fatty acids. In ovine adipose tissue, acetyl-CoA carboxylase appeared to be rate-limiting to lipogenesis, while in bovine subcutaneous adipose tissue, the activity of fatty acid synthetase may have been the limiting step in lipogenesis. In addition, the low activity of ATP-citrate lyase, especially relative to aconitate hydratase, probably limited the conversion of lactate to fatty acids in ovine adipose tissue. It is unlikely that ATP-citrate lyase activity was rate-limiting to lipogenesis from lactate in bovine adipose tissue. The data indicate that extending the results obtained from adipose tissue from one species to lipid metabolism in ruminants in general may not be valid.

show abstract

“…A three-fold decline in mammary blood flow was the probable cause of the decreased glucose extraction rather than any change in acetoacetate concentration. Whether changes similar to those in rats occur in ruminants remains to be shown.It seems unlikely that glucose-sparing mechanisms would be as beneficial to ruminants as to rats, considering the relatively low oxidation of glucose and its minor contribution to fatty acid synthesis.In other words, mechanisms to conserve glucose are active even in fed ruminants Robertson et al (1980). found PDH activity to be low infusions had no effect while L-BHBA was just as effective as D-BHBA Mebane and Madison (1964).…”

mentioning

confidence: 99%

Metabolic characteristics of the ketotic state in the bovine

Mills

View full text Add to dashboard Cite

Pyruvate dehydrogenase and the regulation of glucose metabolism in ruminant tissues

Cited by 15 publications

References 18 publications

Regulation of glycolysis and fatty acid synthesis from glucose in sheep adipose tissue

Regulation of glycolysis and fatty acid synthesis from glucose in sheep adipose tissue

Comparisons of Lipogenesis and Glucose Metabolism between Ovine and Bovine Adipose Tissues

Metabolic characteristics of the ketotic state in the bovine

Contact Info

Product

Resources

About