Acute hemorrhage has been demonstrated to stimulate aldosterone output in dog and man (1-3). Because of the relatively greater increment in aldosterone than in glucocorticoid secretion or excretion, a specific aldosterone-stimulating effect has been postulated. All of these studies, however, were performed in subjects with intact pituitaries. In view of the accumulating evidence (4-8) of the role of ACTH in regulating secretion of aldosterone, especially in the acute experiment, the role of the pituitary in the increment in aldosterone secretion following hemorrhage remains uncertain. The present experiments were designed to compare the effect of acute hemorrhage on aldosterone secretion in normal and in hypophysectomized dogs.
METHODSFifteen male mongrel dogs (9.5 to 15 kg) were studied. The normal group of 5 dogs had the right lumboadrenal vein cannulated by the technique of Hume and Nelson (9) on the day prior to the experiment. At the start of the experiment each dog was anesthetized with Nembutal and the right femoral vein and artery were cannulated, the latter for continuous blood pressure recording, using a Grass model 5 polygraph and a Statham strain gage. Ten-to 15-ml samples of adrenal vein blood were collected. Each sample was immediately replaced by dog bank blood to avoid the effects of intermittent small hemorrhages. After two to three control samples, collected at 20 to 30 minute intervals, 15 ml of blood per kg body weight was withdrawn from the femoral artery within 6 minutes. Collection of the first post-hemorrhage sample of adrenal vein blood was begun 10 minutes after the start of hemorrhage. An additional one or two samples were collected at 20-to 30-* This work has been supported by Grants C-3998 and A-3818 from the United States Public Health Service and a grant-in-aid from The Commonwealth Fund. This report was presented at the meeting of the Federated American Societies for Experimental Biology, Chicago, April, 1960. minute intervals. The shed blood was then transfused over 6 minutes and two to three post-transfusion samples were collected at intervals similar to those of the posthemorrhage period. Following this last sample, 1 IU of ACTH (Upjohn) was administered through the femoral vein and collection of adrenal vein blood was begun 10 minutes later.Ten dogs were hypophysectomized by the transbuccal route (10), and the right adrenal vein was cannulated on the experimental day. One hour after hypophysectomy, collection of adrenal vein samples was begun. The protocol thereafter was similar to that of the normal dogs. Blood samples were centrifuged immediately after collection, and the plasma was separated and frozen for subsequent analysis. Aldosterone and corticosterone were measured by the isotope derivative technique of Kliman and Peterson (11), and 17-dihydroxycorticoids by the Silber-Porter method (12). Secretion rates were calculated from the concentrations and the plasma flow per minute. Completeness of hypophysectomy was checked by gross examination of the hypothalamus and sella ...