Walsh-Reitz M M, Aithal H N, Toback F G
Am J Physiol. 1984 Nov;247(5 Pt 1):C321-6. doi: 10.1152/ajpcell.1984.247.5.C321.
Accelerated kidney growth and increased tissue Na content have been observed in rats fed a K-deficient diet. These observations suggest that enhanced Na influx could mediate renal growth, a hypothesis that was tested in cultures of kidney epithelial cells of the BSC-1 line. Reduction of the K concentration in the culture medium from 5.4 to 3.2 mM augmented cell growth and induced a transient increase in the cellular content of Na and a decrease in that of K. That low-K-induced growth was Na dependent was shown by decreasing the medium Na concentration from 155 to 150 mM, which abolished the increases in both growth and cell Na content in a concentration-dependent manner. The stimulation of glyceraldehyde-3-phosphate dehydrogenase (G3PD) activity that occurs in cells exposed to low-K medium for 1 h was similarly prevented by decreasing the medium Na concentration. Thus decreased availability of extracellular Na prevented the increase in cell Na content, stimulation of G3PD activity, and accelerated growth induced by low-K medium. The hypothesis was also tested by adding vasopressin to cultures of BSC-1 cells exposed to low-K medium; the hormone prevented the increments in cell Na content, G3PD activity, and growth to the same extent as did decreased availability of extracellular Na. These results are consistent with the interpretation that transient accumulation of Na is a critical determinant of the initiation of kidney epithelial cell growth.
在喂食低钾饮食的大鼠中观察到肾脏生长加速和组织钠含量增加。这些观察结果表明，增强的钠内流可能介导肾脏生长，这一假设在BSC-1系肾上皮细胞培养物中得到了验证。将培养基中的钾浓度从5.4 mM降至3.2 mM可促进细胞生长，并导致细胞内钠含量短暂增加和钾含量减少。通过将培养基钠浓度从155 mM降至150 mM表明低钾诱导的生长依赖于钠，这以浓度依赖的方式消除了生长和细胞钠含量的增加。通过降低培养基钠浓度，同样可以防止暴露于低钾培养基1小时的细胞中发生的甘油醛-3-磷酸脱氢酶（G3PD）活性的刺激。因此，细胞外钠可用性的降低阻止了细胞钠含量的增加、G3PD活性的刺激以及低钾培养基诱导的生长加速。通过向暴露于低钾培养基的BSC-1细胞培养物中添加血管加压素也对该假设进行了测试；该激素与细胞外钠可用性降低一样，在相同程度上阻止了细胞钠含量、G3PD活性和生长的增加。这些结果与以下解释一致，即钠的短暂积累是肾上皮细胞生长启动的关键决定因素。
