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Pyruvate inhibition of pyruvate dehydrogenase kinase
Author(s) -
Priestman David A.,
Orfali Karen A.,
Sugden Mary C.
Publication year - 1996
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(96)00877-0
Subject(s) - pyruvate dehydrogenase complex , pyruvate dehydrogenase kinase , pyruvate decarboxylation , pyruvate dehydrogenase phosphatase , pyruvate kinase , pyruvate carboxylase , dihydrolipoyl transacetylase , mitochondrion , endocrinology , medicine , pkm2 , chemistry , in vivo , biochemistry , metabolism , enzyme , biology , glycolysis , microbiology and biotechnology
Both prolonged starvation and hyperthyroidism evoke stable increases in cardiac pyruvate dehydrogenase kinase (PDHK) activity. Pyruvate inhibits PDHK in rat heart mitochondria with activation of PDHC. The sensitivity of PDHK to inhibition by pyruvate declines after prolonged starvation. In the present study, pyruvate concentrations giving 50% active complex (PDHa) in mitochondria from fed, control and fed, hyperthyroid rats were 0.3 and 0.8 mM, respectively, compared with 1.0 and 2.8 mM, respectively in mitochondria from 24‐h‐starved and 48‐h‐starved rats. The results demonstrate that altered pyruvate sensitivity is not of necessity linked with altered PDHK activity. PDHK activities in mitochondria prepared from cardiac myocytes from fed rats were increased after culture for 24 h with dibutyryl cyclic AMP (50 μM) plus n ‐octanoate (1 mM), with a concomitant decline in sensitivity of PDHK to pyruvate inhibition, suggesting that changes in sensitivity of PDHK to pyruvate inhibition in vivo may be secondary to increased fatty acid supply and cyclic AMP concentrations.