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Renal Denervation Restores the Baroreflex Regulation of Renal Sympathetic Nerve Activity in Rats Receiving Intrarenal Bradykinin
Author(s) -
Khan Safia Akhtar,
Sattar Munavvar Zubaid Abdul,
Rathore Hassaan Anwer,
Ahmad Ashfaq,
Abdullah Nor Azizan,
John Edward James
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.848.2
Subject(s) - bradykinin , baroreflex , denervation , medicine , saline , kidney , endocrinology , blood pressure , diuresis , anesthesia , heart rate , receptor
There is evidence that bradykinin (BK) can potentially increase sensory input and thereby contribute to the sympathoexcitation which often associated with deranged cardiovascular homeostasis. This study investigated the role of the renal innervation in cardiopulmonary baroreflex regulation of renal sympathetic nerve activity (RSNA) and heart rate (HR) in rats following intrarenal bradykinin infusion. Rats were anaesthetized by using 1 mL (i.p.) of a chloralose ‐ urethane mixture (16.5 and 250 mg mL −1 respectively). Intrarenal BK or saline (1 mL h −1 ) were infused into the cortico‐medullary border of the ipsilateral kidney in innervated (INN) and denervated (DNX) rats. Acute renal denervation was performed using 10% phenol in absolute alcohol. The low‐pressure or cardiopulmonary receptors were challenged by infusing an acute saline (0.9% NaCL) volume load for 30 min and RSNA recordings were made from the left kidney. Volume expansion in INN rats reduced (P < 0.05) RSNA by 58% during intrarenal saline infusion, whereas intrarenal infusion of BK in INN rats shows non‐significant renal sympathoinhibition by 13%. Bilateral renal denervation produces a profound renal sympathoinhibition by 57% (P < 0.05) during intrarenal saline and 43% (P < 0.05) during BK infusion. Volume expansion does not show any meaningful effect on the changes in MAP or HR in either the INN or DNX groups. The sensitivity of renal sympathoinhibition caused by a saline volume expansion baroreflex are markedly depressed in rats receiving intrarenal bradykinin infusion. However, the sensitivity of baroreflex regulation of RSNA is normalised as kidneys are denervated. These findings reveal a significant role of the renal sensory innervation in the blunted cardiopulmonary baroreflex regulation of RSNA which is mediated by inflammatory challenge to the kidney. Support or Funding Information The authors fully acknowledge the Universiti Sains Malaysia Research Undergraduate (USM‐ RU) grant (1001/PFARMASI/815078) provided by Universiti Sains Malaysia, Malaysia. Safia Akhtar Khan is a recipient of a USM Fellowship Award [P‐FD0091/11(R)] from the Institute of Post‐Graduate Studies (IPS), Universiti Sains Malaysia (USM), Malaysia.Degree of renal sympathoinhibition in response to volume expansion (VEP) challenge in innervated (INN) and denervated (DNX) groups following intrarenal saline and BK infusion. The 5 min prior to commencement of the infusion was taken as baseline (100%). Data were analysed using one‐way ANOVA followed by a Bonferroni post hoc test. Data presented as mean ± SEM.***P < 0.001 vs. Baseline (INN); ###P < 0.001 or ##P < 0.01 vs. Baseline (DNX).Effect of acute saline infusion on heart rate in innervated (INN) and denervated (DNX) groups following intrarenal saline and BK infusion. Data were analysed using one‐way ANOVA followed by a Bonferroni post hoc test. Data presented as mean ± SEM.