Increased endothelin-1 and decreased adrenomedullin gene expression in thestenotic tissue of congenital pelvi-ureteric junction obstruction in children

Objectives To test the hypothesis that the gene expression of endothelin-1 and adrenomedullin may be altered in stenotic tissues of patients with cong enital hydronephrosis caused by pelvi-ureteric junction (PUJ) obstruction. Materials and methods Using real-time reverse transcription-polymerase chai n reaction, mRNA of smooth muscle-constricting endothelin-1 and of smooth m uscle-relaxing adrenomedullin was quantified in tissue specimens of 20 pati ents with PUJ obstruction (mean age 5.1 years, SD 7.0) and of 21 controls w ith normal PUJs (mean age 23.5 years, SD 24.2). Results The amount of endothelin-1 mRNA in stenotic specimens was higher th an in the controls, indicated by significantly lower threshold cycles (Ct v alues) in real-time PCR for the target gene in the obstructive tissue, with mean (SD) values of 24.9 (1.6) and 26.0 (2.1) (P<0.05), respectively. The endothelin-1 CD31 ratio was significantly higher in the patients (P<0.05) t han in controls. In addition, adrenomedullin gene expression in the obstruc ted junctions was significantly lower than in normal junctions, with higher Ct values for the patient group of 26.7 (1.6) vs 25.2 (1.8) (P<0.05) and l ower adrenomedullin mRNA when standardized to glyceraldehyde-3-phosphate de hydrogenase (GAPDH) (P<0.05), CD31 (P<0.01) and smooth muscle <alpha>-actin mRNA (P<0.01). The two groups showed no significant differences for GAPDH and CD31 mRNA content, whereas there was about twice as much <alpha>-actin mRNA in stenotic tissues than in unaffected PUJs. shown by the lower Ct val ues for the patient group of 16.9 (2.0) vs 17.9 (2.6) (P<0.05). Furthermore , endothelin-1, adrenomedullin and <alpha>-actin mRNA amounts were independ ent of age. Conclusion Taken together these results provide evidence that the productio n of autocrine/paracrine acting endothelin-1 and adrenomedullin is altered in tissues of patients with genuine PUJ obstruction, and may be involved in the pathogenesis of congenital hydronephrosis.