Unlike carbohydrate fuels, which enter the body primarily as glucose or sugars that are readily converted to glucose, lipid fuels are heterogeneous with respect to chain length, branching, and unsaturation. The catabolism of fats is primarily a mitochondrial process, but also occurs in peroxisomes. Using a variety of chain-length-specific transport processes and catabolic enzymes, the primary pathways of catabolism of fatty acids involve their oxidative degradation in two-carbon units - a process known as β-oxidation, which produces acetyl-CoA. In muscle, the acetyl-CoA units are used for ATP production in the mitochondria, whereas in liver the acetyl-CoA is catabolized to ketone bodies, primarily acetoacetate and β-hydroxybutyrate, that are exported for energy metabolism in peripheral tissue.
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- Compare the metabolism of acetyl-CoA in liver and muscle. Explain why the liver produces ketone bodies during gluconeogenesis. What prevents hepatic oxidation of acetyl-CoA?
- Review the merits of carnitine usage as a performance enhancer during exercise and as a supplement for geriatric patients.
- Review the current use and mechanism of action of peroxisome proliferator drugs for treatment of dyslipidemia and diabetes.
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