Thyroxine: convesion to triiodothyronine by isolated perfused rat heart.
Thyroxine labeled with carbon-14 and iodine-125 was perfused through surviving rat hearts. Only when unlabeled triiodothyronine was added as a carrier could the newly formed doubly labeled triiodothyronine be isolated. The fact that this triiodothyronine was labeled with the correct ratio of carbon-14 to iodine-125 indicated that it originated from thyroxine. Approximately 5 percent of the initial carbon-14 radioactivity was found in the recovered triiodothyronine.
D000818:Animals; D001345:Autoradiography; D002247:Carbon Isotopes; D002845:Chromatography; D066298:In Vitro Techniques; D007456:Iodine Isotopes; D009206:Myocardium / Q000378:metabolism*; D010477:Perfusion; D051381:Rats; D013974:Thyroxine / Q000378:metabolism*; D014284:Triiodothyronine / Q000032:analysis / Q000096:biosynthesis*
D002247:Carbon Isotopes; D007456:Iodine Isotopes; D014284:Triiodothyronine; D013974:Thyroxine