Abstract
The cerebral ventricles were perfused with sterile artificial cerebrospinal fluid in unanaesthetized dogs from a cannula in the lateral ventricle to a cannula either in the upper cervical subarachnoid space or in the aqueduct of Sylvius. The perfusate was assayed for acetylcholine on rat blood pressure or frog rectus muscle. Even when no eserine was added to the perfusion fluid the output of acetylcholine in 475 samples taken during wakeful state was between 0.01 to 5ng/min in 354 (74.5%) and above 5 ng in 53 (11.2%). No acetylcholine was detected in 68 samples (14.3%). In 129 samples obtained during sleep (excluding periods of REM sleep) no acetylcholine was detected in 75 (58%) samples and an output of less than 1 ng/min was observed in the rest. Acetylcholine appeared in the effluent of samples taken during sleep when rapid eye movements occurred or before waking.
