Amiloride is a Na+ channel blocker and has been used as a diuretic. It mainly inhibits the exchange of Na+-K+ and Na+-H+ in the distal tubule and collecting duct of the kidney, thus increasing the excretion of Na+ and water, reducing the excretion of K+ and H+. Recent studies have found a significant increase in urine uPA in patients with massive proteinuria.Urine uPA concentration were positively correlated with urinary protein and decreased with remission of proteinuria. In children and adults with nephrotic syndrome,as well as rat with proteinuria induced by puromycin amino-nucleoside, amiloride can inhibit uPA concentration in urine, which may be one of the mechanisms of amiloride in reducing proteinuria.