Inhibitory effect of thyroid hormones on pituitary cyclic amp phosphodiesterase activity in vitro.
Thyroid hormones effectively inhibited partially purified cyclic AMP phosphodiesterase from the anterior and posterior lobes of bovine pituitary gland competitively with the substrate, but thyronine, diiodotyrosine, monoiodotyrosine, thyrotropin, thyrotropin releasing hormone, dexamethasone, and luteinizing hormone releasing hormone did not inhibit this enzyme activity. Ki values were found to be 1.0 and 2.5 microM for thyroxine, and 8.0 and 13.5 microM for triiodothyronine in the anterior and posterior lobes, respectively.
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors*; D000818:Animals; D002417:Cattle; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D066298:In Vitro Techniques; D010902:Pituitary Gland / Q000201:enzymology*; D013963:Thyroid Hormones / Q000494:pharmacology*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology; D013974:Thyroxine / Q000494:pharmacology; D014284:Triiodothyronine / Q000494:pharmacology
D013963:Thyroid Hormones; D014284:Triiodothyronine; D007987:Gonadotropin-Releasing Hormone; D013973:Thyrotropin-Releasing Hormone; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D013974:Thyroxine