THE URINARY PHOSPHATE EXCRETION FACTOR OF PARATHYROID GLAND EXTRACTS: A HORMONE OR AN ARTEFACT?1

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Abstract
Multiple and single intraven. injns. of Na citrate into bilaterally nephrectomized dogs caused parathyroid gland stimulation with a resultant rapid and marked hypercalcemia. Thyroparathyroidectomized animals could tolerate only small amts. of citrate and failed to manifest any change in serum Ca. This confirms previous findings that the Ca-mobilizing activity of endogenously produced parathyroid hormone is not contingent on kidney function. That the intraven. injn. of parathyroid gland extract causes an immediate increase in the urinary excretion of inorganic phosphate has been confirmed in the dog. The artefactitious nature of the factor producing this phenomenon is established by the demonstration of its presence in formaldehyde-inactivated parathyroid gland extracts devoid of Ca-mobilizing activity, and in extracts of spleen and of thymus (beef) prepared by a process similar to that for the prepn. of active parathyroid gland extracts. In no instance was a diuresis noted; the reported diuretic activity of parathyroid gland extracts is therefore of no fundamental importance to either the Ca-mobilizing or the phosphate excretion activity of the extracts studied. The chemical soln. hypothesis of parathyroid hormone action is discussed from the standpoint of its irreconcilability with existent data.