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
Abstract
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 µl.min(-1).g(-1)) and absolute sodium excretion (U(Na)V) (1.08 +- 0.27 vs, 6.38 +- 0.76 µmol.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 µl.min(-1).g(-1) recorded in innervated ACF TGR, U(Na)V was 0.31 +- 0.05 vs. 0.04 +- 0.01 µmol 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.