A QUANTITATIVE METHOD FOR THE BIOASSAY OF THE EFFECT OF ADRENAL CORTICAL STEROIDS ON MINERAL METABOLISM

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Abstract
A method based on the depression of the urinary Na24/K42 ratio in adrenalectomized rats is presented. Lowering of the ratio was linearly dependent on the logarithm of a dose of DCA for a range of 0.8-4.0 [mu]g. The slopes of the ratios against logarithm of dose for adrenal cortical extract and the active cortical steroids were found to be linear and parallel with that of DCA. Block variation from test to test necessitated the use of 6-point balanced assays with DCA as the standard. A standard curve could be constructed for the approximate assay of substances by expressing the ratios of the compounds tested as % of concurrent control values as block variation was eliminated by this procedure. All the active compounds tested lowered the urinary Na24/K42 ratio and the activities in terms of DCA showed qualitative and quantitative agreement with the Kuizenga survival time test and the Everse de Fremery muscle test. Progesterone, estradiol and testosterone were inactive. Beef adrenal cortical extract was highly active to an extent which is as yet unexplained.