Direction of carbon flux in starvation and after refeeding: in vitro and in vivo effects of 3-mercaptopicolinate.
3-Mercaptopicolinate (3-MPA) is a specific inhibitor of phosphoenolpyruvate carboxykinase (PEP CK). In vivo the hypoglycaemic action of 3-MPA in 24 h-starved rats was abolished on intragastric glucose refeeding. Nonetheless, 3-MPA decreased hepatic glycogen content and rate of synthesis in starved animals re-fed glucose. The inference is that on re-feeding after starvation hepatic glycogen is synthesised mainly de novo via glyconeogenesis involving PEP CK. 3-MPA increased hepatic lipogenesis in water- and glucose-fed normal and diabetic rats. This increase is presumed to result from inhibition of PEP CK and consequent diversion of pyruvate from gluconeogenesis to lipogenesis. In contrast, 3-MPA inhibited brown-fat lipogenesis in water- and glucose-fed rats.
D002001:Adipose Tissue, Brown / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism; D005215:Fasting; D005260:Female; D005947:Glucose / Q000378:metabolism*; D007657:Ketone Bodies / Q000378:metabolism; D007773:Lactates / Q000378:metabolism; D008055:Lipids / Q000096:biosynthesis; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008112:Liver Glycogen / Q000378:metabolism; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000037:antagonists & inhibitors; D010848:Picolinic Acids / Q000494:pharmacology*; D011773:Pyruvates / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D007657:Ketone Bodies; D007773:Lactates; D008055:Lipids; D008112:Liver Glycogen; D010848:Picolinic Acids; D011773:Pyruvates; C008363:3-mercaptopicolinic acid; D010729:Phosphoenolpyruvate Carboxykinase (GTP); D005947:Glucose