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  • Title: Identification of alpha 1-adrenoceptor subtypes in rat renal proximal tubules.
    Author: Gopalakrishnan SM, Chen C, Lokhandwala MF.
    Journal: Eur J Pharmacol; 1993 Dec 21; 250(3):469-72. PubMed ID: 7906656.
    Abstract:
    Although the existence of alpha 1-adrenoceptor subtypes has been suggested in the kidney, their characterization in the proximal tubules has not been reported. This study was undertaken to characterize the alpha 1-adrenoceptor subtypes in the renal proximal tubules. [3H]Prazosin bound to proximal tubules with a KD of 106 +/- 17 pM and a Bmax of 152 +/- 9 fmol/mg protein. Pretreatment of the tubules with chloroethylclonidine, 100 microM, reduced the Bmax of [3H]prazosin binding by about 50%, indicating the presence of the alpha 1B-adrenoceptor subtype. Competition studies performed with the alpha-adrenoceptor antagonists, WB 4101, (+)-niguldipine, 5-methylurapidil and phentolamine were shallow and could be distinguished into a high affinity (alpha 1A) and a low affinity site (alpha 1B) with an approximately equal distribution of both receptor subtypes. These observations clearly demonstrate the existence of alpha 1A- and alpha 1B-adrenoceptor subtypes in the renal proximal tubules.
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