HAVCR1 and acute kidney injury: While, these studies examined the effect of pretreatment PDE-5 inhibitors such as tadalafil and sildenafil on renal histology, oxidative stress or kidney function, none of them examined the impact of carnitine or PDE-5 inhibitors on the more sensitive biomarkers of AKI, namely NGAL and KIM-1, in AKI setting.