Vasoactive hormones in endotoxin shock: a comparative study in cats and dogs.

1. Entamoeba coli endotoxin was administered intravenously to cats and dogs.2. The changes in circulating levels of catecholamines and angiotensin following endotoxin were assayed by a continuous superfusion technique.3. The response of the dog was characterized by an immediate sustained rise in angiotensin levels and a later variable rise in catecholamine levels.4. The response of the cat was characterized by an early rise in catecholamine levels and a later rise in angiotensin levels.5. It is concluded that this species difference may reflect the relative importance of renin-angiotensin and sympatho-adrenal systems of dogs and cats, respectively.