Post-exercise ketosis and the glycogen content of liver and muscle in rats on a high carbohydrate diet.
Post-exercise ketosis is known to be suppressed by physical training and by a high carbohydrate diet. As a result it has often been presumed, but not proven, that the development of post-exercise ketosis is closely related to the glycogen content of the liver. We therefore studied the effect of 1 h of treadmill running on the blood 3-hydroxybutyrate and liver and muscle glycogen concentrations of carbohydrate-loaded trained (n = 72) and untrained rats (n = 72). Resting liver and muscle glycogen levels were 25%-30% higher in the trained than in the untrained animals. The resting 3-hydroxybutyrate concentrations of both groups of rats were very low: less than 0.08 mmol.l-1. Exercise did not significantly influence the blood 3-hydroxybutyrate concentrations of trained rats, but caused a marked post-exercise ketosis (1.40 +/- 0.40 mmol.l-1 h after exercise) in the untrained animals, the time-course of which was the approximate inverse of the changes in liver glycogen concentration. Interpreting the results in the light of similar data obtained after a normal and low carbohydrate diet it has been concluded that trained animals probably owe their relative resistance to post-exercise ketosis to their higher liver glycogen concentrations as well as to greater peripheral stores of mobilizable carbohydrate.
Adams
J H
JH
Department of Physiology, University of Cape Town Medical School, Observatory, South Africa.
Koeslag
J H
JH
D020155:3-Hydroxybutyric Acid; D000138:Acidosis / Q000517:prevention & control*; D000818:Animals; D001835:Body Weight; D004040:Dietary Carbohydrates / Q000008:administration & dosage* / Q000378:metabolism; D006003:Glycogen / Q000032:analysis*; D006885:Hydroxybutyrates / Q000097:blood; D007657:Ketone Bodies / Q000097:blood; D007662:Ketosis / Q000517:prevention & control*; D008112:Liver Glycogen / Q000032:analysis*; D008291:Malate Dehydrogenase / Q000032:analysis; D008297:Male; D009132:Muscles / Q000032:analysis* / Q000201:enzymology; D010805:Physical Conditioning, Animal; D005082:Physical Exertion / Q000502:physiology; D051381:Rats
D004040:Dietary Carbohydrates; D006885:Hydroxybutyrates; D007657:Ketone Bodies; D008112:Liver Glycogen; D006003:Glycogen; D008291:Malate Dehydrogenase; D020155:3-Hydroxybutyric Acid