Functional expression of the murine D2, D3 and D4 dopamine receptors in Xenopus laevis oocytes

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