Effect of fasting and refeeding on acetyl-CoA carboxylase in rat hindlimb muscle.
Previous studies have demonstrated marked differences in liver acetyl-CoA carboxylase (ACC) activity between fasted rats and fasted rats refed with a fat-free diet. This study was designed to determine whether skeletal muscle ACC responds to dietary manipulation similarly to liver. Male Sprague-Dawley rats were fasted 48 h (F), fasted 48 h and refed fat-free diet for 48 h (R), or were fed normal rat chow ad libitum (A). Liver ACC, measured on resuspended ammonium sulfate precipitates of 48,000 g supernatants of tissue homogenates, was markedly decreased in F (77 +/- 6 nmol.g-1.min-1) and increased in R (562 +/- 37 nmol.g-1.min-1) rats compared with A rats (210 +/- 23 nmol.g-1.min-1). The citrate concentration required to cause half-maximal activation of liver ACC (K0.5) was 1.34 +/- 0.14 mM for F, 0.77 +/- 0.09 mM for R, and 0.87 +/- 0.09 mM for A. The quadriceps muscle, on the other hand, showed no difference in ACC activity or in the K0.5 for citrate activation. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blots confirmed the biochemical measurements, showing marked differences in the size of the protein bands in the +260,000 mol wt range in F vs. R liver ACC preparations but not in skeletal muscle ACC preparations. We conclude that skeletal muscle ACC is controlled by different mechanisms than those observed in liver.
Winder
W W
WW
Zoology Department, Brigham Young University, Provo, Utah 84602, USA.
MacLean
P S
PS
Lucas
J C
JC
Fernley
J E
JE
Trumble
G E
GE
D000103:Acetyl-CoA Carboxylase / Q000378:metabolism*; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D015153:Blotting, Western; D004040:Dietary Carbohydrates / Q000494:pharmacology; D004435:Eating / Q000502:physiology*; D004591:Electrophoresis, Polyacrylamide Gel; D005215:Fasting / Q000502:physiology*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D006003:Glycogen / Q000378:metabolism; D006614:Hindlimb / Q000502:physiology; D007328:Insulin / Q000097:blood; D008112:Liver Glycogen / Q000378:metabolism; D008297:Male; D008970:Molecular Weight; D009124:Muscle Proteins / Q000032:analysis / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D008112:Liver Glycogen; D009124:Muscle Proteins; D006003:Glycogen; D000103:Acetyl-CoA Carboxylase