Acetyl Coenzyme A and Acetylcarnitine Concentration and Turnover Rates in Muscle and Liver of the Ketotic Rat and Guinea Pig
J. D. Erfle 1 and F. Sauer 1
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1 From the Animal Research Institute, Research Branch, Canada Department of Agriculture, Ottawa, Ontario, Canada
Fasting ketosis caused no change in liver acetylcarnitine concentration but caused a decrease in muscle acetylcarnitine to one-half the control level. The combined acetyl coenzyme A and acetylcarnitine turnover rates for control and ketotic liver were, respectively, 4.66 and 10.90 mµmoles per g (fresh weight) per min; for normal and ketotic muscle the corresponding figures were 8.23 and 4.52 mµmoles per g (fresh weight) per min. With respiratory activity unchanged in ketotic liver, any increase in acetyl-CoA or acetylcarnitine turnover rate must reflect an increased rate of acetoacetate synthesis. By contrast, ketotic muscle was characterized by a decreased acetyl-CoA or acetylcarnitine turnover rate, a decreased acetylcarnitine pool size, a shift to a more oxidized state as indicated by measured ratios of lactate to pyruvate, and an increased specific activity of acetyl-CoA and acetylcarnitine. These results explain a previously reported observation that fasted ketotic guinea pigs that have received injections of acetate-1-14C expire less Co2 but more 14CO2 than their appropriate controls.
Submitted on September 6, 1966
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