Changes in catecholamine and angiotensin levels in the cat and dog during hemorrhage.

HALL, RODNEY C., AND ROBERT L. HODGE. Changes in catecholamine and angiotensin levels in the cat and dog during hemorrhage. Am. J. Physiol. 221(5) : 1305-1309. 197 1 .-The changes in the circulating levels of catecholamines and angiotensin were estimated simultaneously in cats and dogs during two different rates of hemorrhage to a constant volume by using an especially developed bioassay technique. In addition, the effect of slow, progressive hemorrhage was studied in the dog. There was a consistent rise in angiotensin levels in all animals and no species difference was observed. At slow rates of hemorrhage, catecholamines rose in the cat but not in the dog; at fast rates, both species showed a rise, but this was higher in the cat. During slow, progressive hemorrhage in dogs, the appearance of angiotensin preceded that of catecholamines. It is concluded that the renin-angiotensin system is important in circulatory homeostasis in moderate hemorrhage in both species, but there is a species difference in the importance of the sympathoadrenal system in this cardiovascular stress.