THE ACTION OF MICRO‐ELECTROPHORETICALLY APPLIED 1‐3,4‐DIHYDROXYPHENYLALANINE (DOPA) ON SINGLE CORTICAL NEURONES

Abstract

1 The technique of microelectrophoresis was used in order to compare the actions of l-3,4-dihydroxyphenylalanine (DOPA) and noradrenaline on single neurones in the cerebral cortices of cats and rats. 2 DOPA could both excite and depress cortical neurones. Cells excited by DOPA were also excited by noradrenaline and cells depressed by DOPA were also depressed by noradrenaline. 3 In the case of both excitatory and depressant responses, DOPA appeared to be less potent than noradrenaline. 4 Responses to DOPA and noradrenaline could be antagonized by phentolamine and propranolol. Responses to acetylcholine were not affected. 5 Responses to acetylcholine, but not responses to DOPA, were antagonized by atropine. 6 The results indicate that locally applied DOPA may mimic the actions of noradrenaline on cortical neurones. Possible mechanisms for these effects of DOPA are discussed.