Abstract
Several Armour thyrotrophin preparations were labeled with different amounts of a fluorescent dye, acid rhodamine B (Lissamine-Rhodamine B 200, Imperial Chemical Industries, Ltd.) following Chadwick's method with slight modifications. The native thyrotrophin lost from 12 to 34% of its biological activity after labeling, proved by Gilliland's method. A portion of the same labeled thyrotrophin was denaturated by heating in acetic acid medium. Different lots of rats were intravenously injected with native labeled thyrotrophin, denaturated labeled thyrotrophin and fluorescent dye solution respectively.
It was observed: 1) Native labeled thyrotrophin declined rapidly in the circulation, though it remained longer than denaturated labeled thyrotrophin. 2) Fluorescence corresponding to native thyrotrophin was seen for a very short time in the thyroid gland and longer in the connective tissue of ocular structures, interstitium of skeletal muscles, perivisceral adipose tissue and mast cells. The Kupffer cells and other macrophages as well as the proximal tubule cells showed the longest accumulation. 3) Fluorescence corresponding to denatured labeled thyrotrophin was not observed in the thyroid gland; it was seen with low intensity in the connective and adipose tissues as well as in the mast cells. It was observed with higher intensity in the macrophages, convoluted tubule cells and it was seen to be eliminated through the epithelium of the small intestine. 4) Rats injected with acid rhodamine B solution eliminated the dye through the urinary and bile systems. In these animals fluorescence was seen only in the macrophages and proximal tubule cells, though in lesser amount compared with the animal injected with labeled hormone.