Bowen J W
Department of Pharmacology, University of Missouri-Columbia School of Medicine 65212.
Am J Physiol. 1992 Apr;262(4 Pt 1):C845-53. doi: 10.1152/ajpcell.1992.262.4.C845.
To determine whether alterations in cell volume affect Na(+)-K(+)-adenosinetriphosphatase (ATPase) expression, a subclone of the Madin-Darby canine kidney (MDCK) cell line was incubated in anisotonic serum-free medium and alpha- and beta-subunit mRNA, Na(+)-K(+)-ATPase activity, and active K+ transport were measured. In medium adjusted to 500 mosmol/kgH2O by adding NaCl, the alpha-subunit mRNA concentration was 2.93 +/- 0.14 (SE) times control and beta-mRNA was 1.93 +/- 0.27 times control. When sucrose was added to increase osmolality, alpha-subunit mRNA increased to 1.85 +/- 0.18 times control. Na(+)-K(+)-ATPase activity of homogenates from cells incubated in 500 mosmol/kgH2O medium for 24 h increased to 2.62 +/- 0.52 times control when NaCl was added and 2.31 +/- 0.34 times control when sucrose was added. Active K+ transport increased between 60 and 90% after cells were incubated in 450 mosmol/kgH2O medium with either NaCl or sucrose added. Stimulation of Na(+)-K(+)-ATPase expression in renal cells facing hypertonic stress may represent a long-term mechanism that allows cells to maintain cation gradients in a hypertonic environment.
为了确定细胞体积的改变是否会影响钠钾-腺苷三磷酸酶（ATP酶）的表达，将马-达二氏犬肾（MDCK）细胞系的一个亚克隆置于等渗无血清培养基中孵育，并检测α和β亚基mRNA、钠钾-ATP酶活性以及活性钾转运。在通过添加氯化钠将培养基渗透压调节至500 mosmol/kgH₂O的条件下，α亚基mRNA浓度为对照的2.93±0.14（标准误）倍，β亚基mRNA为对照的1.93±0.27倍。当添加蔗糖以提高渗透压时，α亚基mRNA增加至对照的1.85±0.18倍。在500 mosmol/kgH₂O培养基中孵育24小时的细胞匀浆，添加氯化钠时钠钾-ATP酶活性增加至对照的2.62±0.52倍，添加蔗糖时增加至对照的2.31±0.34倍。在添加了氯化钠或蔗糖的450 mosmol/kgH₂O培养基中孵育细胞后，活性钾转运增加了60%至90%。面对高渗应激时肾细胞中钠钾-ATP酶表达的刺激可能代表一种长期机制，使细胞能够在高渗环境中维持阳离子梯度。
