Autoradiographic Distribution of Volatile Anesthetics within the Brain

The distribution of volatile anesthetics in the monkey brain was studied with the technique of low-temperature autoradiography, using 14C-labeled halothane, chloroform, diethyl ether, and ethylene. Animals were sacrificed 2, 5, and 20 minutes after administration of the anesthetic. Autoradiographs were prepared from coronal sections of the brain. Results indicate that the early distribution of anesthetics to the gray matter and nuclei is determined primarily by circulatory factors, while the later distribution to the white matter more closely correlates with lipid content, although many exceptions were found. Of particular interest is the high concentration of anesthetic within the reticular formation.