Induction of reactive oxygen species by mechanical stretch drives endothelin production in neonatal pig renal epithelial cells

This study investigated how mechanical stretch of renal tubular epithelium links urinary tract obstruction to early renal microvascular dysfunction in neonates. Using a porcine proximal tubule epithelial cell line (LLC-PK1) and a neonatal pig reversible unilateral ureteral obstruction (rUUO) model, the authors show that mechanical stretch increases oxidant signalling by decreasing catalase while increasing NOX2/NOX4 expression and hydrogen peroxide (H2O2) production. Elevated H2O2 transactivates endothelin converting enzyme-1 (ECE1), driving increased generation of all three endothelin isoforms (ET1–3). In vivo, short-term rUUO increased renal oxidative stress markers, ECE1 activity, and urinary ET1–3, and caused a persistent increase in renal vascular resistance (no-reflow phenotype) even after obstruction relief, consistent with early acute kidney injury. Mechanistically, ET signalling increased receptor-operated Ca2+ entry in neonatal pig renal microvascular smooth muscle via TRPC3, producing sustained vasoconstriction; inhibition of ECE1, endothelin receptors, or TRPC3 improved renal perfusion and reduced early AKI biomarker elevations. Collectively, the work establishes a stretch → NOX/H2O2 → ECE1 → ET1–3 axis that drives neonatal renal hypoperfusion through TRPC3-dependent microvascular constriction.