Pharmacological characterisation and autoradiographic localisation of a putative dopamine D3 receptor in the rat kidney.
The pharmacological profile and the microanatomical localisation of a putative dopamine D3 receptor in the rat renal cortex were investigated using radioligand binding assay and light microscope autoradiography techniques. [3H]7-hydroxy-N,N-di-n-propyl-2-aminotetraline ([3H]7-OH-DPAT) was used as a ligand. [3H]7-OH-DPAT was bound specifically to sections of renal cortex. The binding was time-, temperature- and concentration-dependent, of high affinity and guanine nucleotide-insensitive. The dissociation constant (Kd) value was 0.57 +/- 0.02 nM and the maximum density of binding sites (Bmax) was 62.4 +/- 3.5 fmol/mg tissue. The pharmacological profile of [3H]7-OH-DPAT binding to sections of rat renal cortex suggests the labelling of a dopamine D3 receptor. Light microscope autoradiography revealed the accumulation of the radioligand primarily within cortical tubules and to a lesser extent in the glomerular tuft. In glomeruli, binding sites were found mainly in mesangium and mesangial cells. The demonstration of a putative dopamine D3 receptor in slide-mounted sections of rat renal cortex suggests that appropriate radioligand binding assay techniques combined with autoradiography, may contribute to characterise peripheral dopamine receptor subtypes.
Barili
P
P
Dipartimento di Scienze Farmacologiche e Medicina Sperimentale, Università di Camerino, Italy.
Ricci
A
A
Baldoni
E
E
Mignini
F
F
Amenta
F
F
D000818:Animals; D001345:Autoradiography; D018491:Dopamine Agonists / Q000378:metabolism*; D007672:Kidney Cortex / Q000378:metabolism*; D008297:Male; D011869:Radioligand Assay; D051381:Rats; D017208:Rats, Wistar; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D050637:Receptors, Dopamine D3; D013764:Tetrahydronaphthalenes / Q000378:metabolism*
D018491:Dopamine Agonists; C493595:Drd3 protein, rat; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; D013764:Tetrahydronaphthalenes; C031349:7-hydroxy-2-N,N-dipropylaminotetralin