PARTIAL PURIFICATION AND PROPERTIES OF A “CORTICOTROPIN INFLUENCING FACTOR” (CIF) FROM HUMAN SPINAL FLUID: AN ASSAY METHOD FOR CIF IN THE TRAINED DOG.1

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Abstract
By use of trained dogs with externalized carotid arteries an assay for corticotropin influencing factors has been developed. Injection of cerebrospinai fluid from man or from dog into the carotid artery of such dogs produced a detectable elevation of plasma 17-OHCS within 15 minutes, similar to that observed when 1 μg of ACTH per lb. of body weight was given. A satisfactory dose response curve was obtained when the increased level of 17-OHCS was measured as a function of the amount of spinal fluid (or purified factor) injected into the animal. The factor in spinal fluid can be purified approximately 25-fold by zone electrophoresis on a starch column or on paper. This factor appears to be protein or polypeptide in nature. Present information suggests that the factor may act to stimulate ACTH secretion through the parts of brain irrigated by the carotid artery.