THE ACTION OF MICROELECTROPHORETICALLY APPLIED (3,4‐DIHYDROXY‐PHENYLAMINO)‐2‐IMIDAZOLINE (DPI) ON SINGLE CORTICAL NEURONES

Open Access
Publisher Website
Google Scholar
Abstract
1 The technique of microelectrophoresis was used in order to compare the actions of the imidazoline derivative, (3,4-dihydroxy-phenylamino)-2-imidazoline (DPI), with those of dopamine and phenylephrine on single neurones in the cerebral cortex of the rat anaesthetized with halothane. 2 DPI and phenylephrine were almost exclusively excitatory, whereas dopamine could evoke both excitatory and depressant responses. 3 In the case of excitatory responses, DPI appeared to be more potent than dopamine, and was approximately equipotent with phenylephrine. 4 The dopamine antagonist, haloperidol, could discriminate between excitatory responses to DPI and dopamine: responses to dopamine were abolished, whereas responses to DPI, and to a control agonist, acetylcholine, were unaffected. 5 The α-adrenoceptor antagonist, phenoxybenzamine, antagonized equally excitatory responses to DPI and phenylephrine. Responses to acetylcholine were not affected. 6 It is concluded that DPI does not stimulate dopamine receptors on cortical neurones; the excitatory responses of these cells to DPI may be mediated by α-adrenoceptors.