Reduced TCA Flux in Diabetic Myotubes: Determined by Single Defects?

The diabetic phenotype is complex, requiring elucidation of key initiating defects. Diabetic myotubes express a primary reduced tricarboxylic acid (TCA) cycle flux but at present it is unclear in which part of the TCA cycle the defect is localised. In order to localise the defect we studied ATP prod...

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Main Author: Michael Gaster
Format: Article
Language:English
Published: Wiley 2012-01-01
Series:Biochemistry Research International
Online Access:http://dx.doi.org/10.1155/2012/716056
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author Michael Gaster
author_facet Michael Gaster
author_sort Michael Gaster
collection DOAJ
description The diabetic phenotype is complex, requiring elucidation of key initiating defects. Diabetic myotubes express a primary reduced tricarboxylic acid (TCA) cycle flux but at present it is unclear in which part of the TCA cycle the defect is localised. In order to localise the defect we studied ATP production in isolated mitochondria from substrates entering the TCA cycle at various points. ATP production was measured by luminescence with or without concomitant ATP utilisation by hexokinase in mitochondria isolated from myotubes established from eight lean and eight type 2 diabetic subjects. The ATP production of investigated substrate combinations was significantly reduced in mitochondria isolated from type 2 diabetic subjects compared to lean. However, when ATP synthesis rates at different substrate combinations were normalized to the corresponding individual pyruvate-malate rate, there was no significant difference between groups. These results show that the primary reduced TCA cycle flux in diabetic myotubes is not explained by defects in specific part of the TCA cycle but rather results from a general downregulation of the TCA cycle.
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spelling doaj-art-2e6a6cbd32d64d68ae720a27b49ee66f2025-02-03T06:42:28ZengWileyBiochemistry Research International2090-22472090-22552012-01-01201210.1155/2012/716056716056Reduced TCA Flux in Diabetic Myotubes: Determined by Single Defects?Michael Gaster0Laboratory of Molecular Physiology, Department of Pathology, Odense University Hospital, 5000 Odense, DenmarkThe diabetic phenotype is complex, requiring elucidation of key initiating defects. Diabetic myotubes express a primary reduced tricarboxylic acid (TCA) cycle flux but at present it is unclear in which part of the TCA cycle the defect is localised. In order to localise the defect we studied ATP production in isolated mitochondria from substrates entering the TCA cycle at various points. ATP production was measured by luminescence with or without concomitant ATP utilisation by hexokinase in mitochondria isolated from myotubes established from eight lean and eight type 2 diabetic subjects. The ATP production of investigated substrate combinations was significantly reduced in mitochondria isolated from type 2 diabetic subjects compared to lean. However, when ATP synthesis rates at different substrate combinations were normalized to the corresponding individual pyruvate-malate rate, there was no significant difference between groups. These results show that the primary reduced TCA cycle flux in diabetic myotubes is not explained by defects in specific part of the TCA cycle but rather results from a general downregulation of the TCA cycle.http://dx.doi.org/10.1155/2012/716056
spellingShingle Michael Gaster
Reduced TCA Flux in Diabetic Myotubes: Determined by Single Defects?
Biochemistry Research International
title Reduced TCA Flux in Diabetic Myotubes: Determined by Single Defects?
title_full Reduced TCA Flux in Diabetic Myotubes: Determined by Single Defects?
title_fullStr Reduced TCA Flux in Diabetic Myotubes: Determined by Single Defects?
title_full_unstemmed Reduced TCA Flux in Diabetic Myotubes: Determined by Single Defects?
title_short Reduced TCA Flux in Diabetic Myotubes: Determined by Single Defects?
title_sort reduced tca flux in diabetic myotubes determined by single defects
url http://dx.doi.org/10.1155/2012/716056
work_keys_str_mv AT michaelgaster reducedtcafluxindiabeticmyotubesdeterminedbysingledefects