Fig. 3.
a 3H Raclopride competition curves with the D2likeR agonist quinpirole in D2R cDNA transfected HEK cells with or without cotransfection with δ1R cDNA. The KiH and KiL values obtained were similar and not significantly different. b, c In saturation binding experiments with 3H Raclopride, 1 nM of cocaine lacked effects on the Bmax and KD values in the absence of δ1R cotransfection (b), while a significant increase of the Bmax values (*P < 0.05) was found with cocaine (1 nM) upon cotransfection with δ1R (c). The action by cocaine was significantly counteracted by the sigma 1R antagonist PD144418 (50 nM) (c). Data are presented as the mean ± s.e.m. from five independent experiments performed in triplicate. *P < 0.05 by Student t test