Tissue deposition and metabolism of 125I-labeled synthetic amino-terminal parathyroid hormone bPTH(1-34).

The tissue deposition and metabolism of 125I-labeled synthetic amino-terminal parathyroid hormone, bPTH(1-34), were studied in rats. In comparison with the intact hormone molecule bPTH(1-84), the synthetic fragment was (a) cleared more rapidly from serum; (b) degraded more rapidly in peripheral tissues; (c) deposited to a greater extent in kidney; (d) deposited to a much smaller extent in liver. In bone, the accumulation of total radioactivity was approximately the same with both labeled hormones. The possible physiological significance of these patterns of distribution and metabolism is discussed.