A METHOD FOR MEASURING AND THE EFFECT OF ADRENOCORTICOTROPIC HORMONE ON LIPIDSOLUBLE REDUCING SUBSTANCES OF RABBIT PLASMA*

SATISFACTORY results have been attained in measuring cortin-like substances in urine by chemical methods. It has been possible to develop one of these based on the reduction of phosphomolybdic acid (Heard and Sobel, 1946), so that we can measure the concentration of lipid-soluble reducing substances in blood samples of reasonable size. With this method it is possible to recover 11-desoxy-corticosterone, corticosterone, 17- hydroxy-11-dehydrocorticosterone (Compound E), and the reducing compounds in cortical extracts from bovine adrenal glands, when added to rabbit blood plasma. Measured with a chemical method the excretion of cortin-like substances in the urine of human subjects is markedly increased by the administration of anterior pituitary adrenocorticotropic hormone (ACTH) (Mason et al., 1948; Forsham et al., 1948; Romanoff et al., 1949; Sprague et al., 1950). With our method we have found similar increases in blood plasma values using the rabbit as the experimental animal.