Blood Levels of ACTH in Individual Adrenalectomized Rats

Abstract

Blood levels of ACTH in individual rats 3 and 10 days after bilateral adrenalectomy have been determined by the assay method of Lipscomb and Nelson, using the adrenal venous corticosteroid response of the 2-hr hypophysectomized rat. Three days after adrenalectomy ACTH levels in blood were equivalent to 0.08 μ0.03 mU ACTH/ml; 10 days after adrenalectomy levels were 0.27μ0.05 mU/ml. Pre-rinsing syringes with an acid-gelatin solution prior to collection of donor blood did not significantly alter blood levels of ACTH. The ability to measure ACTH levels in the blood of individual rats 3 and 10 days after adrenalectomy supports the previous finding of an increased sensitivity of ACTH assay with the use of the 2-hr hypophysectomized rat and measurement of adrenal venous effluent corticosterone levels. The data suggest the feasibility of determining ACTH levels in blood of individual intact rats following conditions of stress. (Endocrinology75: 483, 1964)