Ww. Winder et al., EFFECT OF FASTING AND REFEEDING ON ACETYL-COA CARBOXYLASE IN RAT HINDLIMB MUSCLE, Journal of applied physiology, 78(2), 1995, pp. 578-582
Previous studies have demonstrated marked differences in Liver acetyl-
CoA carboxylase (ACC) activity between fasted rats and fasted rats ref
ed with a fat-free diet. This study was designed to determine whether
skeletal muscle ACC responds to dietary manipulation similarly to live
r. Male Sprague-Dawley rats were fasted 48 h (F), fasted 48 h and refe
d fat-free diet for 48 h (R), or were fed normal rat chow ad libitum (
A). Liver ACC, measured on resuspended ammonium sulfate precipitates o
f 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 activati
on of liver ACC (K-0.5) was 1.34 +/- 0.14 mM for F, 0.77 +/- 0.09 mM f
or 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 K-0.5 for citrate
activation. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis
and Western blots confirmed the biochemical measurements, showing mar
ked differences in the size of the protein bands in the +260,000 mol w
t range in F vs. R Liver ACC preparations but not in skeletal muscle A
CC preparations. We conclude that skeletal muscle ACC is controlled by
different mechanisms than those observed in liver.