Na regulates growth of kidney epithelial cells induced by lowering extracellular K concentration
Walsh-Reitz, M.M.; Aithal, H.N.; Toback, F.G.
American Journal of Physiology 247(5 Pt 1): C321-C326
1984
ISSN/ISBN: 0002-9513 PMID: 6496722 Document Number: 237967
Accelerated kidney growth and increased tissue Na have been observed in rats fed on a potassium-deficient diet. The observations suggest that increased sodium influx could mediate renal growth, a hypothesis that was tested in cultures of kidney epithelial cells of the BSC-line. Reduction of K concentration in culture medium from 5.4 to 3.2 mM increased cell growth and induced a transient increase in 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 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 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 increments in cell Na content, G3PD activity, and growth to the same extent as did decreased availability of extracellular Na.