Effects of fasting time on the respiratory quotient and plasma levels of free fatty acids, glucose and urea in adult rats.
The experiments were carried out on 96 male Wistar rats weighing 320-460 g kept either in a warm room (24-26 degrees C) or cold room (15 degrees C). After 0, 3, 6, 12 and 24 hours of fasting determinations were done of: metabolic rate (MR), respiratory quotient (RQ), plasma levels of free fatty acids (FFA), glucose (G) and urea (U), and the glycogen levels in the liver and muscles, as well as total urinary nitrogen excretion in fasted and fed rats. The obtained results showed that changes in the G level in the blood of fasted rats were almost as good an index of changes in carbohydrate metabolism as RQ changes. Changes of U level in the blood of fasted rats reflected fairly well the changes in the amount of catabolized proteins, while FFA level changes were a less accurate index since increased lipolysis may precede considerably increased oxidation of fats.
D000818:Animals; D001786:Blood Glucose / Q000032:analysis*; D005215:Fasting; D005230:Fatty Acids, Nonesterified / Q000097:blood*; D006003:Glycogen / Q000032:analysis; D008099:Liver / Q000032:analysis; D008297:Male; D009132:Muscles / Q000032:analysis; D009584:Nitrogen / Q000652:urine; D051381:Rats; D011919:Rats, Inbred Strains; D012119:Respiration; D013997:Time Factors; D014508:Urea / Q000097:blood*
D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D014508:Urea; D006003:Glycogen; D009584:Nitrogen