Epidermal growth factor and endothelin in cyst fluid from autosomal dominant polycystic kidney disease cases: possible evidence of heterogeneity in cystogenesis.

We determined the concentrations of immunoreactive epidermal growth factor (EGF), endothelin (ET), and cyclic adenosine monophosphate (cAMP) in cyst fluid from 10 nondialyzed patients with autosomal dominant polycystic kidney disease (ADPKD). The concentrations of ET and cAMP in low-sodium cyst fluid (cyst sodium concentration < 100 mEq/L) were significantly increased compared with those in high-sodium cyst fluid (cyst sodium concentration > or = 100 mEq/L), but the concentration of EGF did not differ between the two. There was no relationship between cyst fluid volume and EGF, ET, cAMP values in ADPKD cases. Significant variations of cyst fluid concentrations of EGF, ET, and cAMP were observed among the patients. However, the differences of these variables between the right and left kidney of the individual subjects were unremarkable. Serum levels of creatinine and urea nitrogen showed significant negative correlations with EGF, but not with ET and cAMP. The present data demonstrate the differences in cytokine activity among cysts in ADPKD cases, suggesting the heterogeneity of cystogenesis along the tubular segments in this particular disease.