title: The inhibition of insulin secretion from the perfused rat pancreas after thyroxine treatment.
abstract: Thyroxine treatment did not significantly affect the immediate insulin secretory response of the perfused rat pancreas, but it inhibited the late phase of D-glucose-induced insulin secretion. Thyroxine treatment did not inhibit D-glyceraldehyde-, D-mannose-, and tolbutamide-induced insulin release from the perfused pancreas. An increase in the D-glucose concentration of the perfusion medium as well as feeding of the rats did not restore insulin secretion after thyroxine treatment. The inhibition of D-glucose-induced insulin release in response to thyroxine treatment was reversed after addition of either D-glyceraldehyde, dihydroxyacetone, DL-glyceric acid, pyruvate, or alpha-ketobutyrate to the perfusion medium. Tolbutamide, L-glucose, D-fructose, D-mannose, L-lactate, and propionic acid were not able to overcome the inhibition of D-glucose-induced insulin secretion. Except for alpha-ketobutyrate all substances which were effective in reversing the inhibition of D-glucose-induced insulin release were glycolytic intermediates. Comparing the glycolytic alpha-ketoacid pyruvate and the non-glycolytic ketoacid alpha-ketobutyrate, the only part common to both substances was the ketoacid moiety. It is concluded from these findings that the ketoacid moiety of the alpha-ketoacids plays an important role in reversing the effect of thyroxine on D-glucose-induced insulin release.
mesh_terms: D000818:Animals; D005947:Glucose; D005985:Glyceraldehyde; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects* / Q000378:metabolism; D007651:Keto Acids / Q000378:metabolism; D008297:Male; D008358:Mannose; D010477:Perfusion; D051381:Rats; D013974:Thyroxine / Q000494:pharmacology*; D014044:Tolbutamide
chemical_list: D007328:Insulin; D007651:Keto Acids; D005985:Glyceraldehyde; D014044:Tolbutamide; D005947:Glucose; D008358:Mannose; D013974:Thyroxine