FUNCTIONAL EXPRESSION OF THE MURINE D-2, D-3 AND D-4 DOPAMINE-RECEPTORS IN XENOPUS-LAEVIS OOCYTES

The different marine D2-type dopamine receptors (D-2L, D-2S, D-3L, D-3 S, and D-4) were expressed in Xenopus laevis oocytes, The D2-type rece ptors were all similarly and efficiently expressed in Xenopus oocytes and mere shown to bind the D2 antagonist [I-125]sulpride. They mere al l shown to activate Cl- influx upon agonist stimulation, Using the dia gnostic inhibitor bumetanide, we were able to separate the Na+/K+/2Cl( -) cotransporter component of the Cl- influx from the total unidirecti onal Cl- influx, The D-3L subtype mas found to operate exclusively thr ough the bumetanide-insensitive Cl- influx whereas the other D2-type r eceptors acted on the Na+/K+/2Cl(-) cotransporter as well, The pertuss is toxin sensitivity of the receptor-activated chloride influx via the Na+/K+/2Cl(-) cotransporter varied between the various D2-type recept ors showing that they may couple to different G proteins, and activate different second messenger systems. (C) 1997 Federation of European B iochemical Societies.