Carbamoyl phosphate, an intermediate metabolite of ammonia, was found to be markedly hydrolyzed in the rat brain tissues. This activity was demonstrated with light and electron microscopy certainly being indicated as enzymatic nature, by capturing released phosphate through the activity with lead ions present in the incubating medium. The reaction products were localized mostly in the endoplasmic reticulum and nuclear envelope of the nerve and glial cells. Inner cisternae of the Golgi apparatus were also occasionally stained. The nature of the activity was (1) Briefly fixed tissue with glutaraldehyde showed the best results. Formaldehyde and acetone, on the other hand, markedly destroyed the activity. (2) Sodium fluoride present in the incubating medium completely inhibited the activity, but phloridzin did not. (3) The pH optimum was between 5.0 and 7.0.
These results were compared with those of hepatocytes in relation to glucose 6-phosphatase, acylphosphatase and other phosphatases.