The metabolism of labeled parathyroid hormone. VII Attempts to modify hormone deposition.

Using a 125I-labeled parathyroid hormone with apparently full biological activity, a series of experiments was performed on rats to determine the effects of several physiological parameters on the deposition and metabolism of the hormone in the target tissues, liver, kidney and bone. Among the variables studied were: systemic phosphate levels, systemic calcium levels, calcitonin administration, pregnancy, and dosage (at low levels). Some small variations in deposition and tissue metabolism of the hormone were observed but the invariance of the pattern of deposition and the rapid automatic destruction by target tissues was most impressive.