DOPAMINE D-1 AND D-2 RECEPTORS IN THE HUMAN URETER AND URINARY-BLADDER - A RADIOLIGAND BINDING AND AUTORADIOGRAPHIC STUDY

Objective To analyse the pharmacological profile and the anatomical lo calization of the dopamine D-1 and D-2 receptors in sections of the pe lvic part of the ureter and of the fundus of the urinary bladder. Pati ents, materials and methods Samples of the pelvic part of the meter an d of the fundus of the urinary bladder were taken in men (age range 61 +/- 4 years) who were undergoing lower urinary tract surgery. Biochem ical characterization and autoradiographical techniques were used on f rozen sections of the meter or the urinary bladder. [H-3]-SCH 23390 wa s used as a ligand of dopamine D-1 receptors and [H-3]-spiroperidol as a ligand of dopamine D-2 receptors. Results [H-3]-SCH 23390 and [H-3] -spiroperidol were bound by specific sections of the ureter and of the urinary bladder. The pharmacological profile of the binding was consi stent with the labelling of D-1 and D-2 receptors respectively. Light microscope analysis of the localization of D-1 and D-2 receptors revea led the accumulation of the two radioligands in the tunica muscularis of the meter or of the urinary bladder. Conclusion A possible role of the dopaminergic system in the control of urine flow and of some dysfu nctions of the lower urinary tract is suggested.