CHANGES IN BLOOD ACTH UNDER VARIOUS EXPERIMENTAL CONDITIONS STUDIED BY MEANS OF A CROSS-CIRCULATION TECHNIQUE12

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Abstract
The change as well as the duration of the altered rate of ACTH secretion, in response to stress, were determined by means of a cross-circulation technique. It was demonstrated that the high rate of ACTH secretion, following the application of a severe stress such as unilateral or bilateral adrenal-ectomy, can be maintained for approximately 2 hours, after which time the blood ACTH level gradually diminishes and is not detectable in 6 hours. However, after a milder stress, such as that associated with the cannulation of the femoral blood, blood vessels prior to cross-circulation, a steady moderate rate of ACTH secretion can be maintained throughout a 12-hour period studied. The disappearance of ACTH from the blood 6 hours after a severe stress is not due to increased blood level of adrenal cortical hormones, since it also occurs after bilateral adrenalectomy. Neither is this phenomenon due to exhaustion of pituitary ACTH, for if a second stress is applied at this time, marked elevation of blood ACTH occurs. A biphasic pattern of ACTH secretion was demonstrated following the application of a severe stress.