Wang Lijun, Zhang Chengbiao, Su Xiao-Tong, Lin Dao-Hong, Wu Peng, Schwartzman Michal L, Wang Wen-Hui
Department of Physiology, Harbin Medical University, Harbin, China; and.
Department of Pharmacology, New York Medical College, Valhalla, New York.
Am J Physiol Renal Physiol. 2017 Aug 1;313(2):F254-F261. doi: 10.1152/ajprenal.00102.2017. Epub 2017 Mar 29.
Our aim is to examine the role of PGF receptor (FP), a highly expressed prostaglandin receptor in the distal convoluted tubule (DCT) in regulating the basolateral 40-pS K channel. The single-channel studies demonstrated that PGF had a biphasic effect on the 40-pS K channel in the DCT-PGF stimulated at low concentrations (less than 500 nM), while at high concentrations (above 1 µM), it inhibited the 40-pS K channels. Moreover, neither 13,14-dihydro-15-keto-PGF (a metabolite of PGF) nor PGE was able to mimic the effect of PGF on the 40-pS K channel in the DCT. The inhibition of PKC had no significant effect on the 40-pS K channel; however, it abrogated the inhibitory effect of 5 µM PGF on the K channel. Moreover, stimulation of PKC inhibited the 40-pS K channel in the DCT, suggesting that PKC mediates the inhibitory effect of PGF on the 40-pS K channel. Conversely, the stimulatory effect of PGF on the 40-pS K channel was absent in the DCT treated with DPI, a NADPH oxidase (NOX) inhibitor. Also, adding 100 µM HO mimicked the stimulatory effect of PGF and increased the 40-pS K channel activity in DCT. Moreover, the stimulatory effect of 500 nM PGF and HO was not additive, suggesting the role of superoxide-related species in mediating the stimulatory effect of PGF on the 40-pS K channel. The inhibition of Src family tyrosine protein kinase (SFK) not only inhibited the 40-pS K channel in the DCT but also completely abolished the stimulatory effects of PGF and HO on the 40-pS K channel. We conclude that PGF at low doses stimulates the basolateral 40-pS K channel by a NOX- and SFK-dependent mechanism, while at high concentrations, it inhibits the K channel by a PKC-dependent pathway.
我们的目的是研究前列腺素F受体（FP）在远曲小管（DCT）中高表达，在调节基底外侧40-pS钾通道中的作用。单通道研究表明，PGF对DCT中的40-pS钾通道有双相作用——低浓度（小于500 nM）时刺激PGF，而高浓度（高于1 µM）时，它抑制40-pS钾通道。此外，13,14-二氢-15-酮-PGF（PGF的一种代谢产物）和PGE均无法模拟PGF对DCT中40-pS钾通道的作用。抑制蛋白激酶C（PKC）对40-pS钾通道无显著影响；然而，它消除了5 µM PGF对钾通道的抑制作用。此外，刺激PKC可抑制DCT中的40-pS钾通道，表明PKC介导了PGF对40-pS钾通道的抑制作用。相反，在用NADPH氧化酶（NOX）抑制剂二苯基碘（DPI）处理的DCT中，PGF对40-pS钾通道的刺激作用消失。此外，添加100 µM过氧化氢（HO）可模拟PGF的刺激作用，并增加DCT中40-pS钾通道的活性。此外，500 nM PGF和HO的刺激作用并非相加的，这表明超氧化物相关物质在介导PGF对40-pS钾通道的刺激作用中发挥作用。抑制Src家族酪氨酸蛋白激酶（SFK）不仅抑制了DCT中的40-pS钾通道，还完全消除了PGF和HO对40-pS钾通道的刺激作用。我们得出结论，低剂量的PGF通过一种依赖NOX和SFK的机制刺激基底外侧40-pS钾通道，而在高浓度时，它通过一种依赖PKC的途径抑制钾通道。
