Do carnivorous animals run on ketones or do they run on a mixture of fat and glucose (gluconeogenesis)? Are they simply more efficient at converting protein to glucose than humans? Any information would be appreciated.
asked byforeveryoung (14952)
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on May 29, 2012
at 02:33 PM
Glucose and ketones are complementary substrates for energy production in all mammals. Although we tend to associate them with "starvation" (or glucose starvation) in mammals, ketone bodies such as acetoacetate and ??-hydroxybutyrate are produced by the liver, and tissues such as heart muscle routinely derive much of their metabolic energy from oxidation of these compounds.
"Any standard biochemistry textbook will point out that ketone bodies are routinely being used for fuel in cardiac and skeletal muscle of higher animals. The brain only uses ketone bodies when glucose supplies are very low, such as during starvation '" http://www.jbc.org/content/272/34/21151.full
My bet is that carnivores with very little glucose intake, fuel their central nervous system with a minority of gluconeogensis generated glucose and majority of ketones (as human would), but with advanced gluconeogenesis to supply glycogen for muscles (in humans this process is limited - it's pretty hard to do high intensisty explosive exercise fuelled by gluconeogenesis alone).
I'm pretty much guessing though...