Active and inactive forms of pyruvate dehydrogenase in rat heart and kidney: Effect of diabetes, fasting, and refeeding on pyruvate dehydrogenase interconversion

Wieland, O.; Siess, Elmar A.; Schulze-Wethmar, F.H.; Funcke, H.G.V.; Winton, B.

doi:10.1016/0003-9861(71)90244-x

Cited by 230 publications

(98 citation statements)

References 13 publications

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“…In starved rats, for example, PDHa of heart muscle rose from 7% to 65% and that of kidney from 15% to 78% when the concentration of plasma FFA was normalized by nicotinic acid treatment [5]. In the present study on diabetic rats the amount of heart muscle PDH a was much lower than expected [5] from the plasma FFA concentrations after nicotinic acid treatment, while that of the kidney approached the normal value. As diabetic animals injected with insulin showed a marked increase of PDH a in heart muscle but not in kidney it is reasonable to conclude that insulin is involved in the regulation of PDH interconversion solely in the former organ.…”

Section: Discussioncontrasting

confidence: 48%

“…In an earlier study an inverse relationship between the levels of plasma FFA and PDH a in heart muscle and kidney from intact rats was demonstrated [5]. In starved rats, for example, PDHa of heart muscle rose from 7% to 65% and that of kidney from 15% to 78% when the concentration of plasma FFA was normalized by nicotinic acid treatment [5].…”

Section: Discussionmentioning

confidence: 97%

“…The temperature did not rise above -4~ during homogenization. PDH activities were measured before and after activation with Mg 2+ by the dismutation assay described earlier [5].…”

Section: Preparation Of Tissue Extracts and Pyruvate Dehydrogenase Dementioning

confidence: 99%

“…Previous work from this laboratory had shown that in heart muscle of normal fed rats about two-thirds of total PDH activity was found as PDH a whereas only about one tenth of total activity was found as PDH a in starved or ketoacidotic alloxan diabetic animals. Furthermore, PDHa levels lowered by diabetes and by fasting could be normalized by insulin treatment and by refeeding of carbohydrate, or treatment with nicotinic acid, respectively [5]. From these and other experiments [6,7] it was suggested that the release and oxidation of free fatty acids (FFA) might be an important factor for the regulation of PDH.…”

mentioning

confidence: 96%

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The effect of insulin on pyruvate dehydrogenase interconversion in heart muscle of alloxan-diabetic rats

Öhlén¹,

Siess²,

Löffler³

et al. 1978

Diabetologia

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Summary.Evidence is presented for regulation by insulin of pyruvate dehydrogenase (PDH) interconversion in rat heart muscle in vivo and in vitro. In the alloxan diabetic rat the active (dephospho) enzyme amounted only to 12% of total PDH and was restored to 42% by insulin. Antilipolytic treatment of the diabetic animals was ineffective, indicating that the action of insulin was independent of a lowering of plasma non-esterified fatty acid concentration. On perfusion of isolated hearts from diabetic rats in the presence of glucose the proportion of pyruvate dehydrogenase in the active form remained low but was fully restored upon addition of insulin (2 mU/ml) to the medium. No effect of insulin was obtained in the absence of glucose. The correlation between the rate of pyruvate decarboxylation in the perfused heart and of pyruvate dehydrogenase activity, in vitro, suggests that in the diabetic heart the entry of pyruvate into the citric acid cycle is largely controlled by covalent modification of the pyruvate dehydrogenase complex rather than by feedback inhibition. The possible role of insulin therein is discussed.

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Section: Discussioncontrasting

confidence: 48%

Section: Discussionmentioning

confidence: 97%

“…The temperature did not rise above -4~ during homogenization. PDH activities were measured before and after activation with Mg 2+ by the dismutation assay described earlier [5].…”

Section: Preparation Of Tissue Extracts and Pyruvate Dehydrogenase Dementioning

confidence: 99%

mentioning

confidence: 96%

See 2 more Smart Citations

The effect of insulin on pyruvate dehydrogenase interconversion in heart muscle of alloxan-diabetic rats

Öhlén¹,

Siess²,

Löffler³

et al. 1978

Diabetologia

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show abstract

“…The brains were dissected frozen, weighed and homogenized in 4 vol of 20 mM potassium phosphate buffer, pH 7.0, containing 40% (v/v) glycerol [8], using an Ultraturrax homogenizer. The supratentorial portion of adult rat brain was removed by the rapid blowing and freezing technique [9] and homogenized as just described.…”

Section: Animals and Tissue Preparationmentioning

confidence: 99%