Féraille E, Barlet-Bas C, Cheval L, Rousselot M, Carranza M L, Dreher D, Arystarkhova E, Doucet A, Favre H
Division de Néphrologie, Hôpital Cantonal Universitaire, Geneva 4, Switzerland.
Pflugers Arch. 1995 Jun;430(2):205-12. doi: 10.1007/BF00374651.
Previous studies have demonstrated the presence of two populations of Na,K-ATPase with distinct kinetic, pharmacological and immunological characteristics along the rabbit nephron, indicating that the proximal segments of the nephron express exclusively the alpha 1 isoform of the catalytic subunit, whereas the collecting duct expresses an alpha 3-like isoform. Because pharmacological studies have shown the existence of two populations of Na,K-ATPase with different sensitivities to ouabain in the rat cortical collecting duct, which may result from the presence in the same nephron segment of the two isoforms demonstrated in the different segments of the rabbit nephron, the present study was undertaken to characterize the properties of Na,K-ATPase along the rat nephron. Results indicate that each segment of the rat nephron contains two subpopulations of Na,K-ATPase: a component highly sensitive to ouabain (IC50 approximately 5.10(-6) M) which is recognized by an anti-alpha 3 antibody and another moiety of lower affinity for ouabain (IC50 approximately 5.10(-4) M) which is recognized by an anti-alpha 1 antibody. Whether these two subpopulations correspond to different isoforms of the alpha subunit of Na,K-ATPase (alpha 1 and alpha 3-like) remains to be determined.
先前的研究表明，沿兔肾单位存在具有不同动力学、药理学和免疫学特征的两种钠钾ATP酶群体，这表明肾单位的近端节段仅表达催化亚基的α1同工型，而集合管表达α3样同工型。由于药理学研究表明，大鼠皮质集合管中存在对哇巴因敏感性不同的两种钠钾ATP酶群体，这可能是由于在同一肾单位节段中存在兔肾单位不同节段所显示的两种同工型，因此进行本研究以表征大鼠肾单位中钠钾ATP酶的特性。结果表明，大鼠肾单位的每个节段都包含两种钠钾ATP酶亚群体：一种对哇巴因高度敏感（IC50约为5×10⁻⁶ M），可被抗α3抗体识别；另一种对哇巴因亲和力较低（IC50约为5×10⁻⁴ M），可被抗α1抗体识别。这两个亚群体是否对应于钠钾ATP酶α亚基的不同同工型（α1和α3样）仍有待确定。
