[3H]yohimbine and [3H]idazoxan bind to different sites on rabbit forebrain and kidney membranes.

The binding of the alpha 2-adrenoceptor ligands [3H]yohimbine and [3H]idazoxan to rabbit kidney and forebrain membranes was compared. The maximum number of [3H]yohimbine binding sites was higher than the number of [3H]idazoxan binding sites in forebrain and lower in kidney. Large differences were observed in the ability of noradrenaline, adrenaline, idazoxan, rauwolscine, yohimbine and WY 26392 to displace [3H]yohimbine and [3H]idazoxan from their binding sites. These data suggest that [3H]idazoxan and [3H]yohimbine bind to different sites on rabbit tissue membranes.