title: Inhibition of hepatic gluconeogenesis by the Rp-diastereomer of adenosine cyclic 3',5'-phosphorothioate.
abstract: The specific intracellular cyclic AMP-dependent protein kinase antagonist, the Rp-diastereomer of adenosine cyclic 3',5'-phosphorothioate (Rp-cAMPS), inhibited both basal and cyclic AMP-agonist-induced rates of gluconeogenesis in hepatocytes isolated from fasted rats. Incubation of the cells in the presence of pyruvate and lactate and either the Sp-diastereomer of adenosine cyclic 3',5'-phosphorothioate (Sp-cAMPS) or glucagon produced a concentration-dependent increase in the rate of gluconeogenic glucose production which was shifted to higher concentrations of Sp-cAMPS or glucagon in the presence of Rp-cAMPS. Incubation of the cells with Rp-cAMPS in the absence of agonist produced no increase in the rate of glucose production and, in most cases, 100 microM-Rp-cAMPS resulted in 14-20% decrease in the substrate-stimulated rate of glucose production. Sp-cAMPS-induced gluconeogenesis was inhibited half-maximally at 1 microM-Rp-cAMPS and glucagon-induced gluconeogenesis was inhibited half-maximally at 12 microM-Rp-cAMPS. Approx. 10-15% of the inhibition of gluconeogenesis observed in the presence of Rp-cAMPS was due to conversion of glucose 6-phosphate to liver glycogen, consistent with Rp-cAMPS-induced reactivation of glycogen synthase. The remaining 85-90% inhibition of gluconeogenic glucose production resulted from the action of Rp-cAMPS on the cyclic AMP-sensitive enzymes controlling the rate of gluconeogenesis.
mesh_terms: D000818:Animals; D000242:Cyclic AMP / Q000031:analogs & derivatives* / Q000494:pharmacology; D005934:Glucagon / Q000494:pharmacology; D005943:Gluconeogenesis / Q000187:drug effects*; D006006:Glycogen Synthase / Q000378:metabolism; D066298:In Vitro Techniques; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D011494:Protein Kinases / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013237:Stereoisomerism; D013873:Thionucleotides / Q000494:pharmacology*
chemical_list: D013873:Thionucleotides; C016957:adenosine-3',5'-cyclic phosphorothioate; D005934:Glucagon; D000242:Cyclic AMP; D006006:Glycogen Synthase; D011494:Protein Kinases