Control of malonyl-CoA by glucose and insulin in perfused skeletal muscle.
This study was designed to determine the effects of glucose and insulin on malonyl-CoA, the potent inhibitor of carnitine palmitoyltransferase I, in the gastrocnemius/plantaris muscle group. Isolated rat hindlimbs were perfused with Krebs-Henseleit bicarbonate buffer containing fresh erythrocytes (hematocrit = 41) and albumin in a flow-through mode for 60 min. Two experiments were performed. In the first, hindlimbs were perfused with medium containing no glucose and no insulin (n = 9) or with medium containing 10 mM glucose and 100 microU/ml of insulin (n = 9). Gastrocnemius/plantaris malonyl-CoA was 0.6 +/- 0.1 nmol/g in the absence of glucose and insulin vs. 1.4 +/- 0.1 nmol/g when both glucose and insulin were added. In the second experiment, hindlimbs were perfused with medium containing 10 mM glucose alone, 200 microU insulin alone, or with a combination of 10 mM glucose and 200 microU/ml of insulin (n = 8 for each). Malonyl-CoA was decreased in gastrocnemius/plantaris perfused with glucose alone (0.7 +/- 0.2 nmol/g) and with insulin alone (0.7 +/- 0.1 nmol/g) compared with hindlimbs perfused with the combination of glucose and insulin (1.4 +/- 0.2 nmol/g). We conclude that both glucose and insulin are required for preventing a decline in muscle malonyl-CoA.
Duan
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Zoology Department, Brigham Young University, Provo, Utah 84602.
Winder
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D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002951:Citrates / Q000378:metabolism; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology*; D006614:Hindlimb / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology*; D007773:Lactates / Q000378:metabolism; D008297:Male; D008316:Malonyl Coenzyme A / Q000378:metabolism*; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects; D010477:Perfusion; D010725:Phosphocreatine / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D002951:Citrates; D007328:Insulin; D007773:Lactates; D010725:Phosphocreatine; D008316:Malonyl Coenzyme A; D000255:Adenosine Triphosphate; D005947:Glucose