DOPAMINE D-2-LIKE RECEPTORS IN THE RAT-KIDNEY - EFFECT OF DENERVATION

The effects of monolateral denervation induced by renal artery occlusi on on dopamine D-2-like receptors were assessed in rat kidney using ra dioligand binding assay and autoradiographic techniques. [H-3]spiperon e was used as a ligand. [H-3]spiperone was bound specifically to secti ons of control innervated kidneys with a dissociation constant (K-d) v alue of 0.07 +/- 0.003 nM and a maximum density of binding sites (B-ma x) value of 35.4 +/- 0.16 fmol/mg tissue. Light microscope autoradiogr aphy showed the accumulation of silver grains both in the arterial tre e and in cortical tubules. At the vascular level, [H-3]spiperone bindi ng sites were accumulated primarily in the adventitia and in adventiti a-media transitional zone. In cortical tubules, the higher density of [H-3]spiperone binding sites was noticeable in proximal convoluted tub ules. A few binding sites were also found in the glomerular tuft. In d enervated kidneys, noradrenaline and dopamine levels were reduced by a bout 90% and 60% respectively in comparison with control innervated ki dneys. Denervation reduced the density of [H-3]spiperone binding sites by more than 85%. In denervated kidneys, light microscope autoradiogr aphy showed the disappearance of specific vascular binding sites and a remarkable reduction of tubular [H-3]spiperone binding sites. The abo ve results indicate that the largest majority of renal dopamine D-2-li ke receptors labelled by [H-3]spiperone is prejunctional in location. (C) 1997 Elsevier Science B.V.