DEIODINATION OF THYROXINE BY HEAT-KILLED RAT KIDNEY CORTEX1

Abstract

When viable slices of rat kidney cortex were incubated with a thyroxine-containing medium, there was a rapid uptake of 55% of the thyroxine and production of inorganic iodide. Although similar slices heated for 10 minutes at 100[degree] C prior to the incubation did not consume oxygen, there was still a rapid "uptake" of 50% of the added thyroxine, and considerable production of iodide. Incubation of heat-killed kidney slices for 3 days at 5''C resulted in twice as much deiodination of added thyroxine as was carried out by living tissue under the same circumstances. When tetraiodothyroacetic acid or 3,5,3[image]-triiodothyronine was substituted for thyroxine, deiodination was also noted with the killed tissue, although no more extensive than with the viable.