Renal sympathetic denervation improves pressure-natriuresis relationship in cardiorenal syndrome: insight from studies with Ren-2 transgenic hypertensive rats with volume overload induced using aorto-caval fistula

The aim was to evaluate the effects of renal denervation (RDN) on autoregulation of renal hemodynamics and the pressure-natriuresis relationship in Ren-2 transgenic rats (TGR) with aorto-caval fistula (ACF)-induced heart failure (HF). RDN was performed one week after creation of ACF or sham-operation. Animals were prepared for evaluation of autoregulatory capacity of renal blood flow (RBF) and glomerular filtration rate (GFR), and of the pressure-natriuresis characteristics after stepwise changes in renal arterial pressure (RAP) induced by aortic clamping. Their basal values of blood pressure and renal function were significantly lower than with innervated sham-operated TGR (p < 0.05 in all cases): mean arterial pressure (MAP) (115 +/- 2 vs. 160 +/- 3 mmHg), RBF (6.91 +/- 0.33 vs. 10.87 +/- 0.38 ml.min(-1).g(-1)), urine flow (UF) (11.3 +/- 1.79 vs. 43.17 +/- 3.24 l.min(-1).g(-1)) and absolute sodium excretion (UNaV) (1.08 +/- 0.27 vs, 6.38 +/- 0.76 mu mol.min(-1).g(-1)). After denervation ACF TGR showed improved autoregulation of RBF: at lowest RAP level (80 mmHg) the value was higher than in innervated ACF TGR (6.92 +/- 0.26 vs. 4.54 +/- 0.22 ml.min(-1).g(-1), p < 0.05). Also, the pressure-natriuresis relationship was markedly improved after RDN: at the RAP of 80 mmHg UF equaled 4.31 +/- 0.99 vs. 0.26 +/- 0.09 l.min(-1).g(-1) recorded in innervated ACF TGR, UNaV was 0.31 +/- 0.05 vs. 0.04 +/- 0.01 mu mol min(-1).g(-1) (p < 0.05 in all cases). In conclusion, in our model of hypertensive rat with ACF-induced HF, RDN improved autoregulatory capacity of RBF and the pressure-natriuresis relationship when measured at the stage of HF decompensation.