Sahai A, Goyal M, Tannen R L
Department of Medicine, University of Southern California, Los Angeles.
J Am Soc Nephrol. 1990 Dec;1(6):882-9. doi: 10.1681/ASN.V16882.
A kidney epithelial cell line, LLC-PK1, which does not synthesize prostaglandins, provides an ideal in vitro model system to investigate the effect of prostaglandins in the regulation of renal ammoniagenesis. Previous studies from our laboratory have demonstrated significant increases in glutamine-dependent ammonia and alanine production by rocked cultures of LLC-PK1 cells subjected to either acute metabolic or respiratory acidosis. In the study presented here, experiments were conducted to investigate the role of prostaglandin F2 alpha (PGF2 alpha) and prostaglandin E2 (PGE2) in the response of ammonia metabolism to acute metabolic acidosis by LLC-PK1 cells. A low dose of PGF2 alpha (0.1 ng/mL) dramatically inhibited the stimulatory effect of a low pH (pH 6.8) on ammonia production. In contrast, the inhibition of cytosolically generated alanine was less dramatic and averaged only 20% of the effect on ammonia production. Furthermore, PGF2 alpha increased cellular alpha-ketoglutarate concentration, suggesting an increase in intramitochondrial pH. Thus, the cellular mechanism of PGF2 alpha action appears to involve either interference with the cytosolic pH signal or its translation to the intramitochondrial compartment. The inhibitory response of PGF2 alpha on pH-stimulated ammoniagenesis was progressively lost at higher concentrations. Both low-dose (0.1 ng/mL) and high-dose (10 ng/mL) PGF2 alpha had no significant effect on the basal rates of ammonia and alanine production at pH 7.4. PGE2, on the other hand, did not exhibit any significant response on ammonia or alanine production at either pH 6.8 or 7.4 when given in a wide range of doses.(ABSTRACT TRUNCATED AT 250 WORDS)
一种不合成前列腺素的肾上皮细胞系LLC - PK1，为研究前列腺素在肾氨生成调节中的作用提供了理想的体外模型系统。我们实验室之前的研究表明，遭受急性代谢性或呼吸性酸中毒的LLC - PK1细胞摇瓶培养物中，谷氨酰胺依赖性氨和丙氨酸的产生显著增加。在本研究中，进行了实验以探究前列腺素F2α（PGF2α）和前列腺素E2（PGE2）在LLC - PK1细胞氨代谢对急性代谢性酸中毒反应中的作用。低剂量的PGF2α（0.1 ng/mL）显著抑制了低pH（pH 6.8）对氨产生的刺激作用。相比之下，对胞质中生成的丙氨酸的抑制作用较小，平均仅为对氨产生影响的20%。此外，PGF2α增加了细胞内α - 酮戊二酸浓度，表明线粒体内pH升高。因此，PGF2α作用的细胞机制似乎涉及干扰胞质pH信号或其向线粒体内腔的传递。PGF2α对pH刺激的氨生成的抑制反应在较高浓度时逐渐消失。低剂量（0.1 ng/mL）和高剂量（10 ng/mL）的PGF2α对pH 7.4时氨和丙氨酸的基础产生速率均无显著影响。另一方面，当给予广泛剂量时，PGE2在pH 6.
