Abstract des Autors

Wistar rats were subjected to daily 90 min-swimming sessions for 5 consecutive days and their adrenal function was studied by measuring corticosterone concentration in blood plasma and in adrenals, as well as by in vitro adrenal corticosterone biosynthesis in response to ACTH stimulation. The first 90 min of swimming caused a marked elevation of corticosterone concentration in blood and adrenals, followed by restoration of its pre-exercise level within 8 h in association with a lack of response to ACTH in vitro. After the second swimming session, augmented corticosterone concentration persisted for the 24 h post-exercise recovery period. The in vitro adrenal response to ACTH was suppressed only 24 h after cessation of exercise. In site of the elevated initial level, the 3rd swimming caused a further increase in plasma but not in the adrenal corticosterone concentration. A continuous decrease of plasma corticosterone level was observed after the 4th swimming bout, and a moderate increase after the 5th, followed by a drop below the corresponding values in the control group. Also a low adrenal corticosterone content, associated with a decreased corticosterone production in vitro, was observed. However, the relative adrenal response to ACTH in vitro was rather augmented. Thus, the intense exercise regime continued for 5 days caused a subtotal exhaustion of adrenal reserve, maintaining however, the responsiveness to corticotropin. Verf.-Referat