During ether narcosis (10% diethyl ether v/v) of 30 min in white mice, the brain content of cAMP and cGMP is significantly diminished. By contrast, the liver cAMP and cGMP concentrations are increased 5 and 30 min after beginning narcosis but there is no or little difference, respectively, as compared to controls after 60 min. Liver glycogen content is elevated after 5 min but is diminished after 30 and 60 min as compared to controls. Pretreatment of the animals with the alpha-blocking agent phentolamine and the beta-blocking agent propranolol, respectively, prevents neither the increase in liver cAMP nor the decrease in liver glycogen during ether narcosis. It may be assumed that the changes in the liver and brain contents of cAMP and cGMP during ether application are due to physico-chemical alterations at the cell membrane which result in changes of the activity of the enzymes adenylate cyclase and guanylate cyclase in brain and liver tissue.