This study was designed to measure changes in plasma ACTH concentration after ether exposure of 3 different durations or a “psychological” stress. After “psychological” stress (in a jar without ether for 30 sec) plasma ACTH concentration increased rapidly from a 9:00 AM “basal” value of 23 ± 4 (mean ± SE) to 71 ± 12 pg/ml at 2.5 min and returned to basal values within 20 min. After breathing an ether-saturated atmosphere in a jar for 30 sec, plasma ACTH rose to 154 ± 30 pg/ml at 2.5 min but did not significantly decline by 40 min. With exposure to ether for 2.5 min, plasma ACTH rose to 384 ± 44 pg/ml at 2.5 min, fell significantly by 40 min and approached basal levels by 80 min after beginning ether. With continuous exposure to ether, plasma ACTH increased as in the 2.5 min ether experiment but the high values persisted for the entire 2-hr period of anesthesia. It is concluded that the magnitude and duration of the rise in plasma ACTH concentration are related to the duration and intensity of the ACTH-releasing stimulus. There is no decrease in the ability to maintain elevated ACTH concentrations during 2 hr of ether anesthesia.
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