The quantitative assay of corticotrophin using rats treated with hydrocortisone acetate.

An attempt has been made to modify the Sayers method for the assay of corticotrophin by substituting for hypophysectomy an injection of sufficient hydrocortisone acetate to suppress the release of endogenous pituitary corticotrophin in intact rats over the period of the assay. The results of forty such assays of subcutaneous corticotrophin seem to indicate that this procedure is about 1(1/2) to 2 times as efficient as the original method using hypophysectomized rats. For a 2 + 2 point assay it was necessary to use a minimum of twenty-four to thirty-two rats.