Autoradiographic localization of beta-adrenergic receptors in rat kidney slices using [125I]iodocyanopindolol.

We have used autoradiography of [125I]iodocyanopindolol [( 125I]-ICYP) to define the distribution and localization of beta-adrenergic receptors in the rat kidney. [125I]ICYP, a radiolabeled beta-adrenergic antagonist, proved to be an excellent probe to identify these receptors in kidney slices in that specific [125I]ICYP binding was 1) saturable, 2) competed stereoselectively by the agonist isoproterenol and the antagonist propranolol, and 3) competed by agonists in a classical rank order of potency for beta 1-adrenergic receptors (isoproterenol greater than epinephrine congruent to norepinephrine). Autoradiographic studies demonstrated that specific [125I]ICYP sites were present exclusively in the cortex and outer medulla and were localized in glomeruli, ascending limb, and distal tubule-cortical collecting duct. Autoradiography of probes like [125I]ICYP appears to offer a simple and rapid method to assess distribution of adrenergic receptors in the kidney and presumably in other tissues as well.