Elimination of Na+ and GTP regulation of alpha 2-adrenoceptor-agonist interactions in rat kidney membranes by 4,4'-diisothiocyano-2,2'-stilbene disulfonic acid (DIDS).

Pretreatment of rat kidney membranes with 4,4'-diisothiocyano-2,2'-stilbene disulfonic acid (DIDS) did not affect the Bmax but reduced the affinity of the receptors for antagonist by less than 2-fold. However, such treatment reduced the affinity of the receptors for agonist by several fold by preventing the formation of agonist-receptor-Gi-protein complex. The modulatory effects of GTP and Na+ on alpha 2-adrenoceptor-agonist interactions were also abolished. These results suggest that DIDS acts at multiple sites on alpha 2-adrenoceptor-adenylate cyclase complex.