Plasma endothelin-1 level, measured glomerular filtration rate and effective renal plasma flow in diabetic nephropathy

Background: Endothelin-1 (ET-1) is potent vasoconstrictor peptide which is able to contribute to the functional and structural renal changes. The aim of this study was to investigate the relationship between plasma concentration of ET-1 and indices of renal function in patients with diabetic nephropathy.

Methods: We measured plasma ET-1 levels in 99 patients with type 2 diabetes, divided into two groups according to the values of their glomerular filtration rate (GFR): group I (GFR ≥ 60 mL/min/1.73 m(2); n = 50), group II (GFR ≥ 60 mL/min/1.73 m(2), n = 49), and the control group (n = 30) with clinically healthy subjects who were matched by age and sex. GFR and effective renal plasma flow (ERPF) were measured by the radioisotopic clearance. Other renal function parameters, such as serum concentrations of cystatin C, urea, creatinine, uric acid, 24-h albuminuria and proteinuria were additionally measured.

Results: There were significant differences in plasma concentration of ET-1 among groups I, II and the control group (1.45 vs. 2.40 vs. 0.80 pg/mL, p < 0.001). The correlation between ET-1 and mGFR (r = -0.52, p < 0.001), ERPF (r = -0.42, p < 0.001), albuminuria and proteinuria (r = 0.36, p < 0.001; r = 0.48, p < 0.001) and cystatin C (r = 0.42, p < 0.001) was significant. In multiple regression analyses, only plasma concentration of ET-1 (p < 0.001) and duration of hypertension (p < 0.05) were independently and significantly associated with mGFR.

Conclusion: A higher plasma concentration of ET-1 is independently associated with a decreased value of GFR in patients with diabetic nephropathy.