Blood pressure response to both carotid occlucion and asphyxia, as influenced by intracerebroventricular injection of norepinephrine or epinephrine.

The carotid occlusion response (COR) in dogs was inhibited by 50 and 58% after intracerebroventricular injection of norepinephrine and hydrochloric acid, both at the pH 2.9. After norepinephrine at pH 7, this inhibition was 22%. The COR inhibition was 24% with epinephrine solution of pH 2.4 whereas the same solution at pH 7 produced no inhibition. The injection of drugs solved in acid solution, lead to a decrease in the pH of the cerebrospinal fluid. The response to asphyxia was inhibited by 50% after injection of norepinephrine at pH 2.9, but not after epinephrine at pH 2.4 or hydrochloric acid. Bradycardia was caused by epinephrine in neutral or acid solution and a decrease of arterial blood pressure was seen after epinephrine or norepinephrine in neutral or acid solution.