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Time courses of the responses of pyruvate dehydrogenase activities to short-term starvation in diaphragm and selected skeletal muscles of the rat.

ABSTRACT: In the fed state, the percentages of the pyruvate dehydrogenase complex (PDH) in the active form (PDHa) in diaphragm and a selection of skeletal muscles (adductor longus, soleus, extensor digitorum longus, tibialis anterior, gastrocnemius) ranged from 8% (soleus) to 38% (gastrocnemius). Major decreases in PDHa activities in all of these muscles were observed after 15 h of starvation, by which time activities were less than 40% of the fed values. In general, the response to starvation was observed more rapidly in muscles of high oxidative capacity. The patterns of changes in skeletal-muscle PDH activities during the fed-to-starved transition are discussed in relation to changes in lipid-fuel supply and oxidation.

SUBMITTER: Holness MJ

PROVIDER: S-EPMC1133652 | biostudies-other | 1989 Dec

REPOSITORIES: biostudies-other

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Effects of re-feeding after prolonged starvation on pyruvate dehydrogenase activities in heart, diaphragm and selected skeletal muscles of the rat.

Project description:We investigated the capacity for pyruvate oxidation in skeletal muscle, diaphragm and heart after starvation and re-feeding. Starvation for 48 h decreased pyruvate dehydrogenase (PDH) activity in soleus (by 47%), extensor digitorum longus (64%), gastrocnemius (86%), diaphragm (87%), adductor longus (90%), tibialis anterior (92%) and heart (99%). Chow re-feeding increased PDH activity in all muscles to 43-78% of the fed value within 2 h. However, complete re-activation was not observed for at least 4-6 h, during which time hepatic glycogen was replenished. We discuss the importance of muscle PDH activity in relation to sparing carbohydrate for hepatic glycogen synthesis.

| S-EPMC1133320 | biostudies-other

Isolated murine skeletal muscles utilize pyruvate over glucose for oxidation.

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Project description:As a result of aging, skeletal muscle undergoes atrophy and a decrease in function. This age-related skeletal muscle weakness is known as “sarcopenia.” To understand the changes in gene expression that occur as a result of age in skeletal muscles, we generated a multi-time point gene expression signature throughout the lifespan of mice and rats, as these are the most commonly used species in preclinical research and intervention testing

2023-06-19 | GSE226118 | GEO

2023-06-19 | GSE226117 | GEO

DAC Human Skeletal Muscles Transcriptome

Project description:Data Access Committee EGAC00001002603

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Cross-bridge mechanics estimated from skeletal muscles' work-loop responses to impacts in legged locomotion.

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Dynamic Responses of Barley Root Succinyl-Proteome to Short-Term Phosphate Starvation and Recovery.

Project description:Barley (Hordeum vulgare L.)-a major cereal crop-has low Pi demand, which is a distinct advantage for studying the tolerance mechanisms of phosphorus deficiency. We surveyed dynamic protein succinylation events in barley roots in response to and recovery from Pi starvation by firstly evaluating the impact of Pi starvation in a Pi-tolerant (GN121) and Pi-sensitive (GN42) barley genotype exposed to long-term low Pi (40 d) followed by a high-Pi recovery for 10 d. An integrated proteomics approach involving label-free, immune-affinity enrichment, and high-resolution LC-MS/MS spectrometric analysis was then used to quantify succinylome and proteome in GN121 roots under short-term Pi starvation (6, 48 h) and Pi recovery (6, 48 h). We identified 2,840 succinylation sites (Ksuc) across 884 proteins; of which, 11 representative Ksuc motifs had the preferred amino acid residue (lysine). Furthermore, there were 81 differentially abundant succinylated proteins (DFASPs) from 119 succinylated sites, 83 DFASPs from 110 succinylated sites, 93 DFASPs from 139 succinylated sites, and 91 DFASPs from 123 succinylated sites during Pi starvation for 6 and 48 h and during Pi recovery for 6 and 48 h, respectively. Pi starvation enriched ribosome pathways, glycolysis, and RNA degradation. Pi recovery enriched the TCA cycle, glycolysis, and oxidative phosphorylation. Importantly, many of the DFASPs identified during Pi starvation were significantly overexpressed during Pi recovery. These results suggest that barley roots can regulate specific Ksuc site changes in response to Pi stress as well as specific metabolic processes. Resolving the metabolic pathways of succinylated protein regulation characteristics will improve phosphate acquisition and utilization efficiency in crops.

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Project description:BackgroundType 2 diabetes differs from type 1 diabetes in its pathogenesis. Type 1 diabetic diaphragm has altered gene expression which includes lipid and carbohydrate metabolism, ubiquitination and oxidoreductase activity. The objectives of the present study were to assess respiratory muscle gene expression changes in type 2 diabetes and to determine whether they are greater for the diaphragm than an upper airway muscle.MethodsDiaphragm and sternohyoid muscle from Zucker diabetic fatty (ZDF) rats were analyzed with Affymetrix gene expression arrays.ResultsThe two muscles had 97 and 102 genes, respectively, with at least ± 1.5-fold significantly changed expression with diabetes, and these were assigned to gene ontology groups based on over-representation analysis. Several significantly changed groups were common to both muscles, including lipid metabolism, carbohydrate metabolism, muscle contraction, ion transport and collagen, although the number of genes and the specific genes involved differed considerably for the two muscles. In both muscles there was a shift in metabolism gene expression from carbohydrate metabolism toward lipid metabolism, but the shift was greater and involved more genes in diabetic diaphragm than diabetic sternohyoid muscle. Groups present in only diaphragm were blood circulation and oxidoreductase activity. Groups present in only sternohyoid were immune & inflammation and response to stress & wounding, with complement genes being a prominent component.ConclusionType 2 diabetes-induced gene expression changes in respiratory muscles has both similarities and differences relative to previous data on type 1 diabetes gene expression. Furthermore, the diabetic alterations in gene expression differ between diaphragm and sternohyoid.

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Glucose metabolism in perfused skeletal muscle. Pyruvate dehydrogenase activity in starvation, diabetes and exercise.

Project description:1. The interconversion of pyruvate dehydrogenase between its inactive phosphorylated and active dephosphorylated forms was studied in skeletal muscle. 2. Exercise, induced by electrical stimulation of the sciatic nerve (5/s), increased the measured activity of (active) pyruvate dehydrogenase threefold in intact anaesthetized rated within 2 min. No further increase was seen after 15 min of stimulation. 3. In the perfused rat hindquarter, (active) pyruvate dehydrogenase activity was decreased by 50% in muscle of starved and diabetic rats. Exercise produced a twofold increase in its activity in all groups; however, the relative differences between fed, starved and diabetic groups persisted. 4. Perfusion of muslce with acetoacetate (2 mM) decreased (active) pyruvate dehydrogenase activity by 50% at rest but not during exercise. 5. Whole-tissue concentrations of pyruvate and citrate, inhibitors of (active) pyruvate dehydrogenase kinase and (inactive) pyruvate dehydrogenase phosphate phosphatase respectively, were not altered by excerise. A decrease in the ATP/ADP ratio was observed, but did not appear to be sufficient to account for the increase in (active) pyruvate dehydrogenase activity. 6. The results suggest that interconversion of the phosphorylated and dephosphorylated forms of pyruvate dehydrogenase plays a major role in the regulation of pyruvate oxidation by eomparison of enzyme activity with measurements of lactate oxidation in the perfused hindquarter [see the preceding paper, Berger et al. (1976)] suggest that pyruvate oxidation is also modulated by the concentrations of substrates, cofactors and inhibitors of (active) pyruvate dehydrogenase activity.

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