Vasoactive endothelin (ET) is generated by ET converting enzyme (ECE)-induced proteolytic processing of pro-molecule big ET to biologically active peptides. H₂O₂ has been shown to increase the expression of ECE1 via transactivation of its promoter. The present study demonstrates that H₂O₂ triggered ECE1-dependent ET1-3 production in neonatal pig proximal tubule (PT) epithelial cells. A uniaxial stretch of PT cells decreased catalase, increased NADPH oxidase (NOX)2 and NOX4, and increased H₂O₂ levels. Stretch also increased cellular ECE1, an effect reversed by EUK-134 (a synthetic superoxide dismutase/catalase mimetic), NOX inhibitor apocynin, and siRNA-mediated knockdown of NOX2 and NOX4. Short-term unilateral ureteral obstruction (UUO), an inducer of renal tubular cell stretch and oxidative stress, increased renal ET1-3 generation and vascular resistance (RVR) in neonatal pigs. Despite removing the obstruction, UUO-induced increase in RVR persisted, resulting in early acute kidney injury (AKI). ET receptor (ET_R)-operated Ca²⁺ entry in renal microvascular smooth muscle (SM) via transient receptor potential channel 3 (TRPC3) channels reduced renal blood flow and increased RVR. Although acute reversible UUO (rUUO) did not change protein expression levels of ET_R and TRPC3 in renal microvessels, inhibition of ECE1, ET_R, and TRPC3 protected against renal hypoperfusion, RVR increase, and early AKI. These data suggest that mechanical stretch-driven oxyradical generation stimulates ET production in neonatal pig renal epithelial cells. ET activates renal microvascular SM TRPC3, leading to persistent vasoconstriction and reduction in renal blood flow. These mechanisms may underlie rUUO-induced renal insufficiency in infants.

血管活性内皮素 (ET) 是通过 ET 转化酶 (ECE) 诱导的前分子大 ET 蛋白水解加工成生物活性肽而产生的。H ₂ O ₂已被证明可以通过其启动子的反式激活来增加 ECE1 的表达。本研究表明，H ₂ O ₂触发新生猪近端小管 (PT) 上皮细胞中 ECE1 依赖性 ET1-3 的产生。PT 细胞的单轴拉伸降低了过氧化氢酶，增加了 NADPH 氧化酶 (NOX)2 和 NOX4，并增加了 H ₂ O ₂水平。拉伸还会增加细胞 ECE1，这种效应可被 EUK-134（一种合成的超氧化物歧化酶/过氧化氢酶模拟物）、NOX 抑制剂罗布麻素以及 siRNA 介导的 NOX2 和 NOX4 敲低所逆转。短期单侧输尿管梗阻 (UUO) 是肾小管细胞拉伸和氧化应激的诱导剂，可增加新生猪肾脏 ET1-3 的生成和血管阻力 (RVR)。尽管消除了梗阻，UUO 引起的 RVR 持续增加，导致早期急性肾损伤 (AKI)。ET 受体 (ET _R ) 操作的 Ca ²⁺通过瞬时受体电位通道 3 (TRPC3) 通道进入肾微血管平滑肌 (SM)，从而减少肾血流量并增加 RVR。尽管急性可逆性 UUO (rUUO) 不会改变肾微血管中 ET _R和 TRPC3 的蛋白表达水平，但抑制 ECE1、ET _R和 TRPC3 可防止肾脏灌注不足、RVR 增加和早期 AKI。这些数据表明机械拉伸驱动的氧自由基的产生刺激新生猪肾上皮细胞中ET的产生。ET 激活肾微血管 SM TRPC3，导致持续的血管收缩和肾血流量减少。这些机制可能是 rUUO 引起的婴儿肾功能不全的基础。