Coutry N, Farman N, Bonvalet J P, Blot-Chabaud M
Institut National de la Santé et de la Recherche Médicale U. 246 Unité d'Enseignement et de Recherche Xavier Bichat, Paris, France.
Am J Physiol. 1994 May;266(5 Pt 1):C1342-9. doi: 10.1152/ajpcell.1994.266.5.C1342.
The aim of this study was to examine whether cell volume variations could play a role in the previously reported Na(+)-K(+)-ATPase pump recruitment and/or activation induced by an increase in intracellular Na concentration (Nai) in cortical collecting ducts (CCD). Isolated CCD from kidneys of aldosterone-repleted mice were incubated in hyper-, hypo-, or isosmotic solutions with and without Na to modify Nai and cell volume independently. Nai, cell volume, and the number of basolateral pumps were measured using 22Na, image analysis, and specific [3H]ouabain binding, respectively. Ouabain-sensitive 86Rb uptake was also measured. In CCD with high Nai, pump recruitment and/or activation was observed only when an increase in tubular volume was associated with Na load. Pump recruitment and/or activation was also induced by cell swelling in the absence of Na load. Recruited and/or activated pumps display an affinity for ouabain and a specific activity (ouabain-sensitive Rb uptake per pump unit) similar to basal pumps. We conclude that 1) cell swelling is implied in the process of Nai-dependent pump recruitment and/or activation, 2) cell swelling can promote pump recruitment and/or activation independently of Na load, 3) basal and recruited and/or activated pumps probably correspond to the same Na(+)-K(+)-ATPase isoform.
本研究的目的是检验细胞体积变化是否在先前报道的皮质集合管（CCD）中细胞内钠浓度（Nai）升高所诱导的钠钾ATP酶泵的募集和/或激活过程中发挥作用。从醛固酮充足的小鼠肾脏中分离出的CCD，分别在含有和不含钠的高渗、低渗或等渗溶液中孵育，以独立改变Nai和细胞体积。分别使用22Na、图像分析和特异性[3H]哇巴因结合来测量Nai、细胞体积和基底外侧泵的数量。还测量了哇巴因敏感的86Rb摄取。在Nai较高的CCD中，仅当肾小管体积增加与钠负荷相关时，才观察到泵的募集和/或激活。在无钠负荷的情况下，细胞肿胀也可诱导泵的募集和/或激活。募集和/或激活的泵对哇巴因表现出亲和力，且其比活性（每个泵单位的哇巴因敏感的Rb摄取）与基础泵相似。我们得出结论：1）细胞肿胀参与了依赖Nai的泵募集和/或激活过程；2）细胞肿胀可独立于钠负荷促进泵的募集和/或激活；3）基础泵以及募集和/或激活的泵可能对应于同一种钠钾ATP酶同工型。
