Renal extraction of circulating adiponectin in patients with renovascular hypertension

Abstract

Patients with chronic renal failure are characterized by an elevated plasma adiponectin concentration, which is significantly lowered after successful kidney transplantation. The direct renal clearance and extraction of adiponectin have not yet been documented in humans. Therefore the aim of the study was to estimate separate kidney extraction of adiponectin, by measuring its concentration in the aorta and both renal veins, in patients with renovascular hypertension caused by unilateral renal artery stenosis. In 30 patients with significant (> 70%) unilateral renal artery stenosis, plasma adiponectin was measured in blood samples taken from the aorta, both renal veins and the vena cava inferior below the orifices of the renal veins. Renal venous plasma adiponectin concentrations (both from the kidney with renal artery stenosis and from the contralateral organ) were only numerically lower than the concentrations measured in the aorta (11.10 [8.65-13.56]; 11.12 [8.81-13.42]; 11.35 [8.90-13.80] microg/ml, respectively). Fractional extraction of adiponectin was 5.0 [-1.6-11.0]% in the kidney with renal artery stenosis and 3.0 [-2.4-9.01% in the contralateral "normal" kidney. Slightly higher concentrations of plasma adiponectin were observed in the vena cava inferior below the orifices of the renal veins (11.79 [9.14-14.44] microg/ml). In patients with unilateral renal artery stenosis significant negative correlations were found between plasma adiponectin concentration obtained from the vena cava inferior below the orifices of renal veins and eGFR (r = -0.38; p < 0.05), systolic (r = -0.71; p < 0.0001) and diastolic blood pressure (r = -0.40; p < 0.04), as well as serum triglyceride concentrations (r = -0.64; p < 0.001). The findings indicate that the fractional renal extraction of adiponectin is rather low.