The metabolism of labeled parathyroid hormone. IV. Autoradiographic studies.

Autoradiographs were prepared from tissues of rats sacrificed 10 minutes after injection of biologically active 125I-labeled parathyroid hormone. No radioactivity was seen in intestine and muscle. Deposition in liver was diffuse showing some sinusoidal concentrations. Depostion in kidney was high and, nearly all activity appeared in selected tubules (presumably proximal tubules) in the outer third of the cortex. Specific localization was also seen in bone particularly in the cellular layers of periosteum and endosteum adjacent to bony matrix and to some extent in osteocytes.