Inhibition of [³H]dopamine uptake by platelets by the dopamine‐D₂ receptor agonist RU 24926

Abstract— We have examined the effect of the dopamine‐D₂ receptor agonist RU 24926 (N‐n‐propyl‐di‐β(3‐hydroxy‐phenyl)‐ethylamine HCl) on [³H]dopamine uptake by human platelets. RU 24926 reduced the uptake of [³H] dopamine by platelet‐rich plasma and this affect was not reversed by the dopamine‐D₂ receptor antagonist haloperidol, or the dopamine‐D₁ receptor antagonist SCH 23390 (8‐chloro‐2,3,4,5‐tetrahydro‐3‐methyl‐5‐phenyl‐1H‐3‐benzazepine‐7‐ol). These data suggest that RU 24926 reduces [³H]dopamine uptake by platelets by competing for the dopamine uptake mechanism on the platelet and not by activation of the dopamine‐D₂ receptor. 1991 Royal Pharmaceutical Society of Great Britain