Abstract
Tissue distribution of radioactive carbon yielded from 14C-Urokinase (14C-UK) in the mouse was studied by whole-body and micro-autoradiography. The mice were frozen with acetone-dry-ice at 30min, 1hr and 6hrs after an intraduodenal administration of 14C-UK. Whole-sagittal sections of the frozen mouse, made by a large microtome in a cryostat, dried in a cryostat, were contacted with X-ray film to obtain autoradiogram. For microautoradiography, pieces of tissues were fixed in 10% formalin solution for 24hrs and the material was embedded in paraffin to make 5μm thick sections. These sections were dipped in emulsion (NR-H2 type, Kodak), and the preparation were exposed for 2 weeks. After developing these sections were post-stained with hematoxylin-eosin. The radioactivity of 14C-UK remained at least 6hrs in the intestinal wall of mice. In histological microautoradiograms, the radioactivity of 14C-UK was mainly distributed in intravascular space.
Besides them, the radioactivity of 14C-UK also appeared in thymus, spleen and lymph nodes at 1hr after intraduodenal administration, and then it seemed to be transferred into the lymphoid channels as well as into the intravascular space.
