BACLOFEN BINDING-SITES IN RAT-KIDNEY

The occurrence and distribution of γ-aminobutyric acidB (GABAB) receptor binding sites were examined in cryostat sections of the rat kidney using [3H](-)-baclofen as ligand. Specific binding was saturable and of high affinity, and was characterized by a Kd value of 24.6 nM and a Bmax of 0.17 pmol/mg tissue. Specifically bound [3H](-)-baclofen was displaced by various agonists and antagonists in a manner consistent with their known order of potency at GABAB receptors. Autoradiographic experiments showed baclofen binding to have a characteristic pattern of distribution within the cortex, whereas the medulla was not labeled. These findings are consistent with the presence of GABAB receptors in the kidney cortex, and suggest a role for GABA in the modulation of renal calcium and/or potassium transport. © 1990.