Abstract 335: Isolated Baroreflex Dysfunction May Impair Renal Function

Autonomic and renal dysfunctions are common chronic conditions that frequently coexist in the same individual, and both are associated with significant morbidity and mortality. Aim: To evaluate if total arterial baroreflex abolishment leads to alterations in renal function. Methods: Wistar rats divided into: control (n=9) and SAD (n=9). Sinoaortic denervation (SAD) was performed using the method previously described by Krieger (1964). Metabolic cage was used to evaluate in vivo renal function. BP and HR signals were recorded using a data acquisition system (Codas, 2 kHz). Autonomic function was evaluated by spectral analysis. Colored microspheres (CM) were infused into the left ventricle to determine renal blood flow and resistance changes quantified by spectrophotometry. Ex vivo renal perfusion was used to measure renal function. Results: Neither BP (C: 106 ± 2 vs. SAD: 108 ± 2 mmHg) nor HR (C: 355 ± 7 vs. SAD: 357 ± 15 bpm) were modified by SAD. HRV was decreased in SAD (43 ± 5 vs. C: 103 ± 12 ms2). However, BPV and LF component of BPV, respectly, were increased in SAD (46 ± 10; 6 ± 0.5 mmHg2) compared to C (35 ± 6; 2.6 ± 2 mmHg2). Although BP was similar between groups, it was observed a reduction in cardiac output in denervated animals (85 ± 6 vs. C: 111 ± 7 mL/min, p=0.02) and an increase in total peripheral resistance (1.25 ± 0.03 vs. C: 0.97 ± 0.02 mmHg/mL/min). These alterations resulted in a decreased plasmatic renal flow in SAD group (1.49 ± 0.18 vs. 3.47 ± 0.21 mL/min/g). Water intake and urine volume were higher in SAD (34 ± 1 mL/24h; 26 ± 6 mL) compared to C (25 ± 2 mL/24h; 8 ± 1 mL) and SAD showed proteinuria (0.03 ± 0.01 vs. C: 0.015 ± 0.0005 g/24h). Ex vivo evaluations demonstred a decreased urinary flow (0.07 ± 0.01 vs . C: 0.15 ± 0.01 mL.g-1.min-1) and glomerular filtration rate in SAD group ( 0.5 ± 0.1 vs. C: 0.3 ± 0.01 mL.g-1.min-1). Our data suggest that total baroreflex impairment leads to a renal and peripheral autonomic dysfunction, since SAD induced proteinuria and increased BPV, both markers of functional organ damage. Moreover, even without neurohumoral influence the kidneys from SAD group was not able to work properly. In conclusion, the results obtained in this study provide evidence that the homeostatic role of the baroreflex is essential in the course of changes of renal function.