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 localization of the dopamine D-1 and D-2 receptors in sections of the pelvic part of the ureter and of the fundus of the urinary bladder. Patients, materials and methods Samples of the pelvic part of the meter and of the fundus of the urinary bladder were taken in men (age range 61 +/- 4 years) who were undergoing lower urinary tract surgery. Biochemical characterization and autoradiographical techniques were used on frozen sections of the meter or the urinary bladder. [H-3]-SCH 23390 was 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 consistent with the labelling of D-1 and D-2 receptors respectively. Light microscope analysis of the localization of D-1 and D-2 receptors revealed 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 dysfunctions of the lower urinary tract is suggested.