Abstract

1. Acetylcholine in concentrations of 2.0 to 4.0γ injected into the hypothalamic region of cats anesthetized with urethane caused a small rise in blood pressure followed by a sharp fall lasting one to two minutes. Similar injections into the lateral ventricle gave the same effect, but not so consistently. Control injections of saline were without effect. The fall of blood pressure was still produced after both vagi were cut.

2. Cardiac and respiratory irregularities occurred occasionally.

3. Intraventricular injections of acetylcholine into the unanesthetized cat caused drowsiness which lasted about one hour.