Localization of beta 1- and beta 2-adrenergic receptors in rat kidney by autoradiography.

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Abstract
Beta-Adrenergic receptor subtypes were localized and differentiated in rat kidney slices by in vitro autoradiography using the nonselective beta-antagonist [125I]iodocyanopindolol in the presence of the selective agents betaxolol (beta 1) and zinterol (beta 2). [125I]Iodocyanopindolol binding to kidney sections in the presence of these agents could be differentiated into high- and low-affinity components as predicted by the subtype selectivity of the compounds. Autoradiography revealed that: beta-adrenergic receptors were highly concentrated within the renal cortex, especially in glomeruli and juxtaglomerular granule cells, and to tubular sites in the cortex and medulla; [125I]iodocyanopindolol labeling of the juxtaglomeruluar granule cells was abolished at lower concentrations (10(-8) M) of betaxolol than was the labeling of glomeruli (10(-6)--10(-4) M); and zinterol had little effect on labeling of juxtaglomerular granule cells and glomeruli unless high concentrations were used, whereas the tubular labeling in medulla was much more sensitive to incubation with zinterol. These results indicate that beta 1- and beta 2-adrenergic receptor subtypes are differentially distributed within the kidney: beta 1, predominantly contained in juxtaglomerular granule cells and glomeruli, and beta 2, predominantly in medullary tubules. In vitro autoradiography provides a useful means to examine different receptor populations in discrete tissue areas.