Sundaresan P R, Barac-Nieto M, Stambo G W, Kelvie S L
Department of Pharmacology, University of Rochester Medical Center, New York 14642.
J Cardiovasc Pharmacol. 1989 Jan;13(1):16-24. doi: 10.1097/00005344-198901000-00003.
Rat kidney glomeruli and cortical tubules were obtained by a combination of sieving and differential centrifugation technique. [3H]Prazosin and [3H]rauwolscine were used to identify and quantify the alpha 1- and alpha 2-adrenergic receptors, respectively. In the glomeruli, the alpha 1-adrenoceptor concentration was 27% and alpha 2-adrenoceptor concentration was 33% of the corresponding values in the tubules. Further localization of the tubular alpha-adrenoceptors was undertaken by studies in the isolated basolateral membrane and comparison with values in the crude plasma membrane. alpha 1-Adrenoceptors were enriched 1.54 +/- 0.1 times and alpha 2-adrenoceptors were enriched 1.73 +/- 0.04 times in the basolateral membrane as compared to crude plasma membrane. However, these values were significantly (p less than 0.05) less than the enrichment value of 2.77 +/- 0.3 obtained for the basolateral membrane marker (Na+ + K+)-ATPase. These results suggested the possibility that alpha 1- and alpha 2-adrenoceptors may also be distributed in the brush border membrane. Direct-binding studies in the purified renal brush border membrane indicated alpha 1-adrenoceptor concentration of 82.1 +/- 3.8 and alpha 2-adrenoceptor concentration of 108.2 +/- 9.3 fmol/mg protein. These values were 32 and 17% of the corresponding values in the basolateral membrane. Overall, our results suggest that alpha 1- and alpha 2-adrenoceptors are present both in the basolateral and brush border membranes analogous to what has been reported for angiotensin and insulin receptors; their primary concentration, however, is in the basolateral membranes.
通过筛分和差速离心技术相结合的方法获取大鼠肾肾小球和皮质肾小管。分别使用[³H]哌唑嗪和[³H]萝芙木碱来鉴定和定量α1 -和α2 -肾上腺素能受体。在肾小球中，α1 -肾上腺素能受体浓度为肾小管中相应值的27%，α2 -肾上腺素能受体浓度为33%。通过对分离的基底外侧膜进行研究并与粗质膜中的值进行比较，对肾小管α -肾上腺素能受体进行进一步定位。与粗质膜相比，基底外侧膜中α1 -肾上腺素能受体富集了1.54±0.1倍，α2 -肾上腺素能受体富集了1.73±0.04倍。然而，这些值显著低于（p < 0.05）基底外侧膜标记物（Na⁺ + K⁺）-ATP酶所获得的2.77±0.3的富集值。这些结果提示α1 -和α2 -肾上腺素能受体也可能分布在刷状缘膜中的可能性。在纯化的肾刷状缘膜中进行的直接结合研究表明，α1 -肾上腺素能受体浓度为82.1±3.8，α2 -肾上腺素能受体浓度为108.2±9.3 fmol/mg蛋白。这些值分别是基底外侧膜中相应值的32%和17%。总体而言，我们的结果表明，α1 -和α2 -肾上腺素能受体存在于基底外侧膜和刷状缘膜中，这与血管紧张素和胰岛素受体的报道情况类似；然而，它们主要集中在基底外侧膜中。
