Existence of renal alpha 1- and alpha 2-adrenoceptors in the human kidney: radioligand binding study in membranes from the human renal cortex and medulla.
We investigated alpha 1- and alpha 2-adrenoceptors by radioligand binding studies in plasma membranes from the human renal cortex and medulla using a new alpha 1-adrenoceptor antagonist, 3H-bunazosin, and an alpha 2-adrenoceptor antagonist, 3H-rauwolscine. Human kidneys were obtained post-mortem (n = 4) or at surgery for carcinoma of the kidney (n = 10). The specific binding of both radioligands was rapid, saturable, reversible and specific. Scatchard analysis of 3H-bunazosin binding showed that the renal cortex had a KD of 4.6 nmol/l and a Bmax of 34.7 fmol/mg of protein, and the medulla a KD of 2.4 nmol/l and a Bmax of 23.2 fmol/mg. The specific binding of 3H-rauwolscine had a KD of 5.6 nmol/l and Bmax of 22.4 fmol/mg of protein for the cortex and values of 5.1 and 42.0, respectively, for the medulla. Competitive inhibition studies suggested that the binding of both radioligands was to sites with alpha 1 and alpha 2 specificity, respectively. The present studies demonstrate that human renal plasma membranes from both the cortex and medulla contain binding sites with both alpha 1- and alpha 2-adrenoceptors.
D006801:Humans; D007668:Kidney / Q000378:metabolism*; D007672:Kidney Cortex / Q000378:metabolism*; D007679:Kidney Medulla / Q000378:metabolism*; D008566:Membranes / Q000378:metabolism; D011799:Quinazolines / Q000378:metabolism; D011869:Radioligand Assay; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D015016:Yohimbine / Q000378:metabolism
D011799:Quinazolines; D011942:Receptors, Adrenergic, alpha; D015016:Yohimbine; C018176:bunazosin