Über die Dopadecarboxylase und Histidindecarboxylase des Nervengewebes

Summary

• 1. In extracts of different parts of the nervous system the activity of l(-)dopa decarboxylase is determined manometrically by measuring the formation of carbon dioxide in nitrogen-atmosphere. Highest activity is found in extracts of postganglionic sympathetic nerves (splenic nerves), sympathetic ganglia (ggl. stellatum) and the sympathetic trunk; lower activity in extracts of the spinal cord and brain stem; lowest activity—nearly none—in cerebral cortex. Extracts of praeganglionic sympathetic nerves and of the Vagus have very low, the phrenic nerve none activity.

• 2. Addition of pyridoxalphosphate—the codecarboxylase—raises the activity of the extracts four to five fold. In brain extracts only by addition of pyridoxalphophate dopa decarboxylase activity is detectable.

• 3. m-Hydroxy- and Dihydroxyphenylserine were only very little decarboxylated. Pyridoxalphosphate scarcely activated.

• 4. The activity of histidine-decarboxylase was determined by incubating the extracts with l-histidine and testing the histamine content of the incubated extracts on the isolated guinea-pig ileum. Highest activity was found in splenic nerves and in the ggl. stellatum, lower activity in the phrenic and vagal nerve, lowest in the spinal cord, brain-stem and cerebral cortex.

• 5. The results strongly indicate, that the formation of hydroxytyramine by l (-) dopa decarboxylase not only represents an intermediary step in the nor-adrenaline synthesis, but that this synthesis can be performed by the nervous tissue itself.