Effects of hyperthyroidism on glucose, glutamine and ketone-body metabolism in the gut of the rat.
1. The metabolism of glucose, glutamine and ketone-bodies was studied in the small intestine of rats after 5 days of hyperthyroidism. 2. Portal-drained visceral bloodflow increased by 20.1% (P < 0.05) in hyperthyroid rats and was accompanied by a decrease in the arteriovenous concentration difference of glutamine (25.7%, P < 0.05), glutamate (22.0%, P < 0.05), alanine (20.9%, P < 0.05) and ammonia (20.6%, P < 0.05) and an increase in that of glucose (27.2%, P < 0.05), lactate (28.9%, P < 0.05) and ketone-bodies (163.2%, P < 0.001). 3. The gut of hyperthyroid rats showed increased rates of extraction of glucose, lactate and ketone-bodies. 4. Enterocytes isolated from hyperthyroid rats showed increased rates of utilization of glucose and ketone-bodies but that of glutamine were decreased. 5. The maximal activities of hexokinase, 6-phosphofructokinase, pyruvate kinase, citrate synthase and oxoglutarate dehydrogenase were increased (by 13.7-36.2%) in intestinal mucosal scrapings of hyperthyroid rats, whereas the activity of glutaminase was decreased (22.1-31.4%). 6. It is concluded that hyperthyroidism increases the rates of utilization of glucose and ketone-bodies but decreases that of glutamine (both in vivo and in vitro) by the epithelial cells of the small intestine.
Ardawi
M S
MS
Department of Clinical Biochemistry, College of Medicine and Allied Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia.
Khoja
S M
SM
D000818:Animals; D001158:Arteries; D001786:Blood Glucose / Q000378:metabolism; D002952:Citric Acid Cycle; D005947:Glucose / Q000378:metabolism*; D005973:Glutamine / Q000097:blood / Q000378:metabolism*; D006019:Glycolysis; D006980:Hyperthyroidism / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000201:enzymology; D007421:Intestine, Small / Q000098:blood supply / Q000378:metabolism*; D007657:Ketone Bodies / Q000097:blood / Q000378:metabolism*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D014680:Veins
D001786:Blood Glucose; D007657:Ketone Bodies; D005973:Glutamine; D005947:Glucose