HYPOTENSION AND LOSS OF PRESSOR RESPONSE TO ANGIOTONIN AS THE RESULT OF TRAUMA TO THE CENTRAL NERVOUS SYSTEM AND SEVERE HEMORRHAGE.

1. Angiotonin refractoriness and hypotension follow upon injury to the central nervous system in dogs and cats. Refractoriness does not develop when the nervous system is quickly and expertly destroyed or the activity of the nervous system depressed by widespread injection into it of a local anesthetic. The syndrome develops in the absence of the kidneys and the suprarenal glands. 2. Glycine, methyl isothiourea, and rest are the only agents studied which tend to restore responsiveness, and the first two of these have only an irregular and temporary effect. 3. There is a marked degree of specificity in the syndrome since undiminished pressor responses to adrenalin, tyramine, methyl isothiourea are observed during complete angiotonin refractoriness. 4. Despite the prolonged hypotension, change in the amount of plasma proteins and in the hematocrit readings is not striking. 5. Parallelism seems to exist between the fall in blood pressure after trauma to the nervous system and development of angiotonin refractoriness. After the syndrome has developed, elevation of the blood pressure by the injection of gum acacia solution or whole blood does not restore the responsiveness to angiotonin. 6. Angiotonin refractoriness and hypotension also develop after marked hemorrhage. Suprarenalectomy or nephrectomy does not prevent its appearance.