Abstract
Summary
Within 48 hours, parathyroidectomy lowers the serum Ca in non-nephrec-tomized mature rats from 10.7 to 8.3 mg %. In the same period of time the serum Ca in nephrectomized-parathyroidectomized rats decreases from 9.6 to 6.5 mg %.
The injection of 5 × 20 units of PTH into normal rats, after 48 hours produces an average elevation of the serum Ca of 1.5 mg %. The injection of the same quantity of PTH into parathyroidectomized-nephrec-tomized rats, after the same time produces an average elevation of the serum Ca of 4 mg % (from 6.5-10.5 mg %). Although these experiments prove that PTH raises the blood Ca without the intermediation of the kidneys, they do not exclude the possibility that the hormone may under normal conditions also affect renal function.
Conclusion. (1) The serum Ca elevating activity of the parathyroid hormone is demonstrable in bilaterally nephrectomized rats. (2) Confirming previous observations, it has been found that “osteitis fibrosa” is produced by PTH injection in the absence of the kidneys.
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