title: Skeletal muscle type comparison of pyruvate dehydrogenase phosphatase activity and isoform expression: effects of obesity and endurance training.
abstract: Pyruvate dehydrogenase (PDH) plays an important role in regulating carbohydrate metabolism in skeletal muscle. PDH is activated by PDH phosphatase (PDP) and deactivated by PDH kinase (PDK). Obesity has a large negative impact on skeletal muscle carbohydrate metabolism, whereas endurance training has been shown to improve regulatory control of skeletal muscle carbohydrate metabolism, more so when coupled with obesity. A majority of this literature has focused on PDK, with little information available on PDP. To determine the relative role of PDP in regulating skeletal muscle PDH activity with obesity and endurance training, obese and lean Zucker rats remained sedentary or were endurance trained (1 h/day, 5 days/wk) for a period of 8 wk. Soleus, red gastrocnemius, (RG), and white gastrocnemius (WG) muscles were sampled after the training period. The main findings were 1) obesity resulted in a 46% decrease in PDP activity expressed per milligram extracted mitochondrial protein only in RG, while PDP isoform content was unchanged; 2) 8 wk of endurance training led to a significant 1.4-2.2-fold increase in PDP activity of all muscle examined from obese rats, and the concomitant increase in PDP1 protein was only seen in soleus and RG; 3) 8 wk of endurance training led to a trending 1.4-2.2-fold increase in PDP activity of all muscle examined from obese rats, and the concomitant increase in PDP1 protein was only seen in soleus and RG; and 4) PDP2 protein content was not affected by obesity or training. These results suggest that decreased PDP activity in oxidative skeletal muscles may play a role in the impairment of carbohydrate metabolism in obese rats, which is reversible with endurance training.
authors: Centre for Muscle Metabolism and Biophysics and Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontario, Canada. pleblanc@brocku.ca
authors: Paul J
authors: PJ
authors: Leblanc
authors: Matthew
authors: M
authors: Mulligan
authors: Anamaria
authors: A
authors: Antolic
authors: Laura
authors: L
authors: Macpherson
authors: J Greig
authors: JG
authors: Inglis
authors: Dale
authors: D
authors: Martin
authors: Brian D
authors: BD
authors: Roy
authors: Sandra J
authors: SJ
authors: Peters
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight / Q000502:physiology; D002950:Citrate (si)-Synthase / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood; D007328:Insulin / Q000097:blood; D007527:Isoenzymes / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology; D018482:Muscle, Skeletal / Q000201:enzymology*; D009765:Obesity / Q000097:blood / Q000503:physiopathology*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D030481:Pyruvate Dehydrogenase (Lipoamide) / Q000378:metabolism; D011769:Pyruvate Dehydrogenase (Lipoamide)-Phosphatase / Q000378:metabolism*; D051381:Rats; D011924:Rats, Zucker
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D007527:Isoenzymes; D030481:Pyruvate Dehydrogenase (Lipoamide); C065640:pyruvate dehydrogenase E1alpha subunit; D002950:Citrate (si)-Synthase; D011769:Pyruvate Dehydrogenase (Lipoamide)-Phosphatase