Logan J L
Research Service, Tucson VA Medical Center, Ariz. 85723, USA.
Nephron. 1995;71(4):433-41. doi: 10.1159/000188764.
The hypothesis that protein metabolites regulate renal growth has been considered for decades, and the overall objective of this work was to test this hypothesis in vitro using an established line of renal tubular epithelial cells, NRK-52E. The addition of urea to the medium of confluent cultures stimulated DNA synthesis which was dependent on the concentration of urea, but independent of the presence of serum. Urea enhanced proliferation of subconfluent cultures of NRK cells in the presence of dilute serum to a similar degree as epidermal growth factor (EGF). Either deletion of serum from the medium or allowing the cultures to achieve confluence prevented the proliferative response to urea, but not EGF. Ammonium chloride stimulated the uptake of 3H-thymidine but did not increase cell number. Ammonium chloride increased the uptake of 3H-leucine and total cellular protein/DNA, while urea had no effect on these markers of growth. The rate of hydrolysis of urea to ammonia in vitro was not altered by the presence of NRK cells. These results suggest that urea and ammonia may regulate renal mass, and that their actions are separate and different.
蛋白质代谢产物调节肾脏生长这一假说已被探讨了数十年，本研究的总体目标是利用已建立的肾小管上皮细胞系NRK - 52E在体外验证这一假说。向汇合培养物的培养基中添加尿素可刺激DNA合成，该刺激依赖于尿素浓度，但与血清的存在无关。在稀释血清存在的情况下，尿素增强了NRK细胞亚汇合培养物的增殖，其程度与表皮生长因子（EGF）相似。从培养基中去除血清或使培养物达到汇合状态均可阻止对尿素的增殖反应，但对EGF无此影响。氯化铵刺激了³H - 胸腺嘧啶核苷的摄取，但未增加细胞数量。氯化铵增加了³H - 亮氨酸的摄取以及细胞总蛋白/DNA含量，而尿素对这些生长标志物无影响。NRK细胞的存在并未改变尿素在体外水解为氨的速率。这些结果表明，尿素和氨可能调节肾脏质量，且它们的作用是相互独立且不同的。
