Catecholamine synthesis in the chromaffin tissue of the African lungfish, Protopterus aethiopicus.

The activities of dopamine-beta-hydroxylase (DBH, E.C. 1.14.17.1) and phenylethanol-N-methyl transferase (PNMT, E.C.1.1.1.10) were determined in tissue homogenates from the chromaffin tissue containing atrium and intercostal arteries from the African lungfish. Clearly measurable activities of DBH were found in both kinds of tissues, while PNMT activity was ascertained only in the intercostal arteries. The activity of DBH in the atrium indicates a possibility for local synthesis of the large amounts of catecholamines, especially noradrenaline, found in this tissue. Catecholamines synthetized in and released from the chromaffin tissues of Protopterus, may be of great importance for the adrenergic control in this animal in the absence of a well developed sympathetic nervous system.