Dopamine D2-like receptors in the rat kidney: effect of denervation.
The effects of monolateral denervation induced by renal artery occlusion on dopamine D2-like receptors were assessed in rat kidney using radioligand binding assay and autoradiographic techniques. [3H]spiperone was used as a ligand. [3H]spiperone was bound specifically to sections of control innervated kidneys with a dissociation constant (Kd) value of 0.07 +/- 0.003 nM and a maximum density of binding sites (Bmax) value of 35.4 +/- 0.16 fmol/mg tissue. Light microscope autoradiography showed the accumulation of silver grains both in the arterial tree and in cortical tubules. At the vascular level, [3H]spiperone binding sites were accumulated primarily in the adventitia and in adventitia-media transitional zone. In cortical tubules, the higher density of [3H]spiperone binding sites was noticeable in proximal convoluted tubules. A few binding sites were also found in the glomerular tuft. In denervated kidneys, noradrenaline and dopamine levels were reduced by about 90% and 60% respectively in comparison with control innervated kidneys. Denervation reduced the density of [3H]spiperone binding sites by more than 85%. In denervated kidneys, light microscope autoradiography showed the disappearance of specific vascular binding sites and a remarkable reduction of tubular [3H]spiperone binding sites. The above results indicate that the largest majority of renal dopamine D2-like receptors labelled by [3H]spiperone is prejunctional in location.
Barili
P
P
Dipartimento di Scienze Farmacologiche e Medicina Sperimentale, Università di Camerino, Italy.
Sabbatini
M
M
Soares-da-Silva
P
P
Amenta
F
F
D000818:Animals; D001345:Autoradiography; D003714:Denervation; D004298:Dopamine / Q000378:metabolism; D018492:Dopamine Antagonists / Q000378:metabolism; D007668:Kidney / Q000294:innervation / Q000378:metabolism*; D008024:Ligands; D008297:Male; D009638:Norepinephrine / Q000378:metabolism; D011869:Radioligand Assay; D051381:Rats; D017208:Rats, Wistar; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D012077:Renal Artery / Q000293:injuries; D013134:Spiperone / Q000378:metabolism
D018492:Dopamine Antagonists; D008024:Ligands; D017448:Receptors, Dopamine D2; D013134:Spiperone; D004298:Dopamine; D009638:Norepinephrine