Abstract 13744: Renal Afferent Nerve Stimulation Induces Baroreflex Resetting Without Compromising Arterial Pressure Buffering Function
Background: Chronic kidney disease induces sympathoexcitation, and nephrectomy results in sympathoinhibition. Recent clinical trials indicated that renal nerve ablation markedly decreased arterial pressure (AP) and suppressed sympathetic nerve activity (SNA). It appears that the kidney serves as the source of sympathoexcitation. We investigated how the renal afferent nerve stimulation (RANS) impacts on baroreflex function by opening the baroreflex feedback loop.
Methods/Results: In anesthetized rats, we opened the baroreflex loop by vascularly isolating the bilateral carotid sinuses and controlled intra-sinus pressure (CSP). We recorded splanchnic SNA and measured AP. Protocol 1 (electrical RANS): In 8 rats, we changed CSP stepwise from 60 to 180 mmHg with or without electrical RANS (10 Hz, 1-3 V). Increases in CSP decreased SNA (the CSP-SNA relation: the neural arc), while decreases in SNA decreased AP (the SNA-AP relation: the peripheral arc). The electrical RANS increased SNA and shifted the CSP-SNA relation upward (Fig. 1A, ΔSNA=14.5±3.8%, p<0.05), whereas unchanged the SNA-AP relation (Fig. 1B). The total open-loop baroreflex gain (from CSP to AP) remained unchanged (1.2±0.2 vs. 1.2±0.2, p=ns). Protocol 2 (chemical RANS): In 7 rats, we changed CSP stepwise from 60 to 180 mmHg with or without chemical RANS (pelvic infusion of 0.15 M KCl, 25 ul/min). The chemical RANS increased SNA and shifted the CSP-SNA relationship upward (Fig. 2A, ΔSNA=5.93±0.9%, p<0.05), whereas unchanged the SNA-AP relation (Fig. 2B). The total open-loop baroreflex gain remained unchanged (1.3±0.3 vs. 1.5±0.2, p=ns).
Conclusion: Both electrical and chemical RANSs induce sympathoexcitation through baroreflex resetting. The fact that the baroreflex gain remains unaltered suggests that the renal deafferentiation by ablation lowers AP via sympathoinhibition without compromising AP buffering function.
- © 2012 by American Heart Association, Inc.