Objective To investigate the relationship between aquaporin -1,-2,-3,-4 mRNA (AQP1-4) and renal parenchyma thickness in congenital hydronephrotic kidney in children.

Methods The expression of aquaporin 1,-2,-3, and -4 mRNA in hydronephrotic kidney of 37 children (aged 60.28±48.8 months) were evaluated with congenital hydronephrosis and normal kidney of 6 children (aged 62.67±17.06 months) using semi-quantitative reverse transcriptase polymerase chain reaction technique. Hydronephrotic kidney parenchyma thickness were measured by B-Ultrasound preoperatively and verified at operation. The relation of aquaporin 1,-2,-3, and -4 mRNA to the hydronephrotic kidney parenchyma thickness were analyzed by linear regression.

Results The aquaporin 1,-2,-3, and -4/beta-actin ratio in the hydronephrotic kidney and normal kidney were AQP1:0.39±0.22 VS 0.90±0.10; AQP2:0.42±0.20 VS 0.92±0.09; AQP3: 0.52±0.22 VS 0.98±0.12; AQP4: 0.30±0.18 VS 0.74±0.21, respectively, and the differences were significant (p<0.01). Hydronephrotic kidney parenchyma thickness measured by B-Ultrasound is averaged at 5.01±2.38 mm, which is identical with those measured at operation. Significant correlation was found between the levels of aquaporin 1,-2,-3,and -4 mRNA and hydronephrotic kidney parenchyma thickness (r = 0.773, 0.772, 0.557, 0.625, respectively; p<0.01).

Conclusions Significant correlation exists between decreased expressions of aquaporin 1,-2,-3, and -4 mRNA and atrophic change of renal parenchyma, providing evidence to explain the mechanism why the thinner renal parenchyma thickness, the weaker renal concentration and dilution function.