1
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Salman IM. Key challenges in exploring the rat as a preclinical neurostimulation model for aortic baroreflex modulation in hypertension. Hypertens Res 2024; 47:399-415. [PMID: 37919429 DOI: 10.1038/s41440-023-01486-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 10/02/2023] [Accepted: 10/06/2023] [Indexed: 11/04/2023]
Abstract
Electrode-based electrophysiological interfaces with peripheral nerves have come a long way since the 1960s, with several neurostimulation applications witnessing widespread clinical implementation since then. In resistant hypertension, previous clinical trials have shown that "carotid" baroreflex stimulation using device-based baroreflex activation therapy (BAT) can effectively lower blood pressure (BP). However, device-based "aortic" baroreflex stimulation remains untouched for clinical translation. The rat is a remarkable animal model that facilitates exploration of mechanisms pertaining to the baroreceptor reflex and preclinical development of novel therapeutic strategies for BP modulation and hypertension treatment. Specifically, the aortic depressor nerve (ADN) in rats carries a relatively pure population of barosensitive afferent neurons, which enable selective investigation of the aortic baroreflex function. In a rat model of essential hypertension, the spontaneously hypertensive rat (SHR), we have recently investigated the aortic baroreceptor afferents as an alternate target for BP modulation, and showed that "low intensity" stimulation is able to evoke clinically meaningful reductions in BP. Deriving high quality short-term and long-term data on aortic baroreflex modulation in rats is currently hampered by a number of unresolved experimental challenges, including anatomical variations across rats which complicates identification of the ADN, the use of unrefined neurostimulation tools or paradigms, and issues arising from anesthetized and conscious surgical preparations. With the goal of refining existing experimental protocols designed for preclinical investigation of the baroreflex, this review seeks to outline current challenges hindering further progress in aortic baroreflex modulation studies in rats and present some practical considerations and recently emerging ideas to overcome them. Aortic baroreflex modulation.
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Affiliation(s)
- Ibrahim M Salman
- Department of Pharmaceutical Sciences, College of Pharmacy, Alfaisal University, Riyadh, Saudi Arabia.
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2
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Salman IM. Functional symmetry of the aortic baroreflex in female spontaneously hypertensive rats. J Hypertens 2023; 41:1456-1465. [PMID: 37382160 DOI: 10.1097/hjh.0000000000003493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/30/2023]
Abstract
BACKGROUND Altered baroreflex function is well documented in hypertension; however, the female sex remains far less studied compared with males. We have previously demonstrated a left-sided dominance in the expression of aortic baroreflex function in male spontaneously hypertensive rats (SHRs) and normotensive rats of either sex. If lateralization in aortic baroreflex function extends to hypertensive female rats remains undetermined. This study, therefore, assessed the contribution of left and right aortic baroreceptor afferents to baroreflex modulation in female SHRs. METHOD Anesthetized female SHRs (total n = 9) were prepared for left, right and bilateral aortic depressor nerve (ADN) stimulation (1-40 Hz, 0.2 ms, 0.4 mA for 20 s) and measurement of reflex mean arterial pressure (MAP), heart rate (HR), mesenteric vascular resistance (MVR) and femoral vascular resistance (FVR). All rats were also matched for the diestrus phase of the estrus cycle. RESULTS Reflex (%) reductions in MAP, HR, MVR and FVR were comparable for both left-sided and right-sided stimulation. Bilateral stimulation evoked slightly larger ( P = 0.03) reductions in MVR compared with right-sided stimulation; however, all other reflex hemodynamic measures were similar to both left-sided and right-sided stimulation. CONCLUSION These data show that female SHRs, unlike male SHRs, express similar central integration of left versus right aortic baroreceptor afferent input and thus show no laterization in the aortic baroreflex during hypertension. Marginal increases in mesenteric vasodilation following bilateral activation of the aortic baroreceptor afferents drive no superior depressor responses beyond that of the unilateral stimulation. Clinically, unilateral targeting of the left or right aortic baroreceptor afferents may provide adequate reductions in blood pressure in female hypertensive patients.
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Affiliation(s)
- Ibrahim M Salman
- Department of Pharmaceutical Sciences, College of Pharmacy, Alfaisal University, Riyadh, Saudi Arabia
- Division of Pulmonology, Allergy and Immunology, Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
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3
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Salman IM. Differential frequency-dependent reflex summation of the aortic baroreceptor afferent input. Pflugers Arch 2023:10.1007/s00424-023-02820-0. [PMID: 37219603 DOI: 10.1007/s00424-023-02820-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 05/15/2023] [Accepted: 05/15/2023] [Indexed: 05/24/2023]
Abstract
Reflex summation in the expression of left and right aortic baroreflex control of hemodynamic functions was investigated. In anesthetized Sprague-Dawley rats, mean arterial pressure (MAP), heart rate (HR), and mesenteric vascular resistance (MVR) were recorded following left, right, and bilateral stimulation of the aortic depressor nerve (ADN). Stimulation frequency was varied between low (1 Hz), moderate (5 Hz), and high (20 Hz). At 1 Hz, left and right ADN stimulation evoked similar depressor, bradycardic and MVR responses, whereas bilateral stimulation induced larger MAP, HR, and MVR reductions compared with stimulations of either side. The sum of the separate and combined stimulation effects on MAP, HR, and MVR was similar, indicating an additive summation. A similar additive summation was observed with HR responses at 5 and 20 Hz. Left-sided and bilateral stimulation produced greater depressor and MVR responses than right-sided stimulation, with responses of the bilateral stimulation mimicking those of the left side. The bilateral MAP or MVR response was smaller than the sum of the separate responses, suggesting an inhibitory summation. In conclusion, reflex summation of the left and right aortic baroreceptor afferent input is differentially expressed in relation to the frequency of the input signal. Summation of baroreflex control of HR is always additive and independent of stimulation frequency. Summation of baroreflex control of MAP is additive when the frequency input is small and inhibitory when the frequency input is moderate to high, with MAP changes mainly driven by parallel baroreflex-triggered changes in vascular resistance.
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Affiliation(s)
- Ibrahim M Salman
- Department of Pharmaceutical Sciences, College of Pharmacy, Alfaisal University, Riyadh, 11533, Saudi Arabia.
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4
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Ameer OZ. Hypertension in chronic kidney disease: What lies behind the scene. Front Pharmacol 2022; 13:949260. [PMID: 36304157 PMCID: PMC9592701 DOI: 10.3389/fphar.2022.949260] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 09/26/2022] [Indexed: 12/04/2022] Open
Abstract
Hypertension is a frequent condition encountered during kidney disease development and a leading cause in its progression. Hallmark factors contributing to hypertension constitute a complexity of events that progress chronic kidney disease (CKD) into end-stage renal disease (ESRD). Multiple crosstalk mechanisms are involved in sustaining the inevitable high blood pressure (BP) state in CKD, and these play an important role in the pathogenesis of increased cardiovascular (CV) events associated with CKD. The present review discusses relevant contributory mechanisms underpinning the promotion of hypertension and their consequent eventuation to renal damage and CV disease. In particular, salt and volume expansion, sympathetic nervous system (SNS) hyperactivity, upregulated renin–angiotensin–aldosterone system (RAAS), oxidative stress, vascular remodeling, endothelial dysfunction, and a range of mediators and signaling molecules which are thought to play a role in this concert of events are emphasized. As the control of high BP via therapeutic interventions can represent the key strategy to not only reduce BP but also the CV burden in kidney disease, evidence for major strategic pathways that can alleviate the progression of hypertensive kidney disease are highlighted. This review provides a particular focus on the impact of RAAS antagonists, renal nerve denervation, baroreflex stimulation, and other modalities affecting BP in the context of CKD, to provide interesting perspectives on the management of hypertensive nephropathy and associated CV comorbidities.
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Affiliation(s)
- Omar Z. Ameer
- Department of Pharmaceutical Sciences, College of Pharmacy, Alfaisal University, Riyadh, Saudi Arabia
- Department of Biomedical Sciences, Faculty of Medicine, Macquarie University, Sydney, NSW, Australia
- *Correspondence: Omar Z. Ameer,
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5
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Low intensity stimulation of aortic baroreceptor afferent fibers as a potential therapeutic alternative for hypertension treatment. Sci Rep 2022; 12:12242. [PMID: 35851099 PMCID: PMC9293925 DOI: 10.1038/s41598-022-15761-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 06/29/2022] [Indexed: 11/17/2022] Open
Abstract
Carotid baroreceptor stimulation has been clinically explored for antihypertensive benefits, but neuromodulation of aortic baroreceptor afferents remains unexplored for potential translation into the clinic. Published studies have used supramaximal stimulations, which are unphysiological and energy inefficient. The objective of the present study was to identify optimal low-charge nerve stimulation parameters that would provide a clinically-relevant (20–30 mmHg) decrease in mean arterial pressure (MAP) in anesthetized spontaneously hypertensive rats. Stimulations of 20 s were delivered to the left aortic depressor nerve (ADN) of these rats using low ranges of pulse amplitudes (≤ 0.6 mA), widths (≤ 0.5 ms) and frequencies (≤ 5 Hz). We also assessed the effects of continuous (20 s) versus intermittent (5 s ON/3 s OFF and 5 s ON/3 s OFF for 20 s) stimulation on MAP, heart rate (HR), mesenteric (MVR) and femoral (FVR) vascular resistance using low (5 Hz) and high (15 Hz) frequencies. Lower pulse amplitudes (0.2 mA) produced 9 ± 2 to 18 ± 2 mmHg decreases in MAP. Higher pulse amplitudes (0.4 mA) produced a median MAP reduction of 28 ± 4 mmHg at 0.2 ms and 5 Hz, with no added benefit seen above 0.4 mA. Continuous and intermittent low frequency stimulation at 0.4 mA and 0.2 ms produced similar sustained decreases in MAP, HR, MVR and FVR. Continuous high frequency stimulation at 0.4 mA and 0.2 ms produced larger reductions in MAP, HR, MVR and FVR compared with all low frequency and/or intermittent high frequency stimulations. We conclude from these findings that “low intensity intermittent” electrical stimulation is an effective alternate way for neuromodulation of the aortic baroreceptor afferents and to evoke a required restoration of MAP levels in spontaneously hypertensive rats. This approach enables low energy consumption and markedly lowers the excessive decreases in MAP and hemodynamic disturbances elicited by continuous high-charge injection protocols.
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Sata Y, Burke SL, Eikelis N, Watson AMD, Gueguen C, Jackson KL, Lambert GW, Lim K, Denton KM, Schlaich MP, Head GA. Renal Deafferentation Prevents Progression of Hypertension and Changes to Sympathetic Reflexes in a Rabbit Model of Chronic Kidney Disease. Hypertension 2021; 78:1310-1321. [PMID: 34538104 DOI: 10.1161/hypertensionaha.121.17037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Yusuke Sata
- Neuropharmacology Laboratory (Y.S., S.L.B., A.M.D.W., C.G., K.L.J., K.L., G.A.H.), Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Human Neurotransmitters Laboratory (Y.S., M.P.S., G.W.L., N.E.), Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Faculty of Medicine, Nursing and Health Sciences, Central Clinical School (Y.S.), Monash University, Melbourne, VIC, Australia.,Department of Cardiology, Alfred Hospital, Melbourne, VIC, Australia (Y.S.)
| | - Sandra L Burke
- Neuropharmacology Laboratory (Y.S., S.L.B., A.M.D.W., C.G., K.L.J., K.L., G.A.H.), Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Nina Eikelis
- Human Neurotransmitters Laboratory (Y.S., M.P.S., G.W.L., N.E.), Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Iverson Health Innovation Research Institute and School of Health Sciences, Swinburne University of Technology, Hawthorn, VIC, Australia (N.E., G.W.L.)
| | - Anna M D Watson
- Neuropharmacology Laboratory (Y.S., S.L.B., A.M.D.W., C.G., K.L.J., K.L., G.A.H.), Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Department of Diabetes, Central Clinical School (A.M.D.W.), Monash University, Melbourne, VIC, Australia
| | - Cindy Gueguen
- Neuropharmacology Laboratory (Y.S., S.L.B., A.M.D.W., C.G., K.L.J., K.L., G.A.H.), Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Kristy L Jackson
- Neuropharmacology Laboratory (Y.S., S.L.B., A.M.D.W., C.G., K.L.J., K.L., G.A.H.), Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences (K.L.J), Monash University, Melbourne, VIC, Australia
| | - Gavin W Lambert
- Human Neurotransmitters Laboratory (Y.S., M.P.S., G.W.L., N.E.), Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Iverson Health Innovation Research Institute and School of Health Sciences, Swinburne University of Technology, Hawthorn, VIC, Australia (N.E., G.W.L.)
| | - Kyungjoon Lim
- Neuropharmacology Laboratory (Y.S., S.L.B., A.M.D.W., C.G., K.L.J., K.L., G.A.H.), Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, VIC, Australia (K.L.)
| | - Kate M Denton
- Cardiovascular Program, Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, VIC, Australia (K.M.D.)
| | - Markus P Schlaich
- Human Neurotransmitters Laboratory (Y.S., M.P.S., G.W.L., N.E.), Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Departments of Cardiology and Nephrology, Dobney Hypertension Centre, School of Medicine, Royal Perth Hospital Unit, University of Western Australia, Royal Perth Hospital (M.P.S.)
| | - Geoffrey A Head
- Neuropharmacology Laboratory (Y.S., S.L.B., A.M.D.W., C.G., K.L.J., K.L., G.A.H.), Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Department of Pharmacology (G.A.H.), Monash University, Melbourne, VIC, Australia
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7
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Li S, Hildreth CM, Rahman AA, Barton SA, Wyse BF, Lim CK, Pilowsky PM, Phillips JK. Renal denervation does not affect hypertension or the renin-angiotensin system in a rodent model of juvenile-onset polycystic kidney disease: clinical implications. Sci Rep 2021; 11:14286. [PMID: 34253766 PMCID: PMC8275789 DOI: 10.1038/s41598-021-93575-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 06/21/2021] [Indexed: 12/17/2022] Open
Abstract
We examined the effect of total and afferent renal denervation (RDN) on hypertension and the renin-angiotensin system (RAS) in a rodent model of juvenile-onset polycystic kidney disease (PKD). Lewis Polycystic Kidney (LPK) and control rats received total, afferent or sham RDN by periaxonal application of phenol, capsaicin or normal saline, respectively, and were monitored for 4-weeks. Afferent RDN did not affect systolic blood pressure (SBP) determined by radiotelemetry in either strain (n = 19) while total RDN significantly reduced SBP in Lewis rats 4-weeks post-denervation (total vs. sham, 122 ± 1 vs. 130 ± 2 mmHg, P = 0.002, n = 25). Plasma and kidney renin content determined by radioimmunoassay were significantly lower in LPK vs. Lewis (plasma: 278.2 ± 6.7 vs. 376.5 ± 11.9 ng Ang I/ml/h; kidney: 260.1 ± 6.3 vs. 753.2 ± 37.9 ng Ang I/mg/h, P < 0.001, n = 26). These parameters were not affected by RDN. Intrarenal mRNA expression levels of renin, angiotensinogen, angiotensin-converting enzyme (ACE)2, and angiotensin II receptor type 1a were significantly lower, whereas ACE1 expression was significantly higher in the LPK vs. Lewis (all P < 0.05, n = 26). This pattern of intrarenal RAS expression was not changed by RDN. In conclusion, RDN does not affect hypertension or the RAS in the LPK model and indicates RDN might not be a suitable antihypertensive strategy for individuals with juvenile-onset PKD.
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Affiliation(s)
- Sheran Li
- Department of Biomedical Sciences, Faculty of Medicine, Human and Health Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - Cara M Hildreth
- Department of Biomedical Sciences, Faculty of Medicine, Human and Health Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - Ahmed A Rahman
- Department of Biomedical Sciences, Faculty of Medicine, Human and Health Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - Sean A Barton
- Department of Biomedical Sciences, Faculty of Medicine, Human and Health Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - Benjamin F Wyse
- Department of Biomedical Sciences, Faculty of Medicine, Human and Health Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - Chai K Lim
- Department of Biomedical Sciences, Faculty of Medicine, Human and Health Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - Paul M Pilowsky
- Discipline of Physiology, School of Medical Sciences, University of Sydney, Sydney, Australia
| | - Jacqueline K Phillips
- Department of Biomedical Sciences, Faculty of Medicine, Human and Health Sciences, Macquarie University, Sydney, NSW, 2109, Australia.
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8
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Saha M, Sun QJ, Hildreth CM, Burke PGR, Phillips JK. Augmented Respiratory-Sympathetic Coupling and Hemodynamic Response to Acute Mild Hypoxia in Female Rodents With Chronic Kidney Disease. Front Physiol 2021; 12:623599. [PMID: 34113258 PMCID: PMC8185289 DOI: 10.3389/fphys.2021.623599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 04/15/2021] [Indexed: 11/15/2022] Open
Abstract
Carotid body feedback and hypoxia may serve to enhance respiratory–sympathetic nerve coupling (respSNA) and act as a driver of increased blood pressure. Using the Lewis polycystic kidney (LPK) rat model of chronic kidney disease, we examined respSNA in adult female rodents with CKD and their response to acute hypoxia or hypercapnia compared to Lewis control animals. Under urethane anesthesia, phrenic nerve activity, splanchnic sympathetic nerve activity (sSNA), and renal sympathetic nerve activity (rSNA) were recorded under baseline conditions and during mild hypoxic or hypercapnic challenges. At baseline, tonic SNA and blood pressure were greater in female LPK rats versus Lewis rats (all P < 0.05) and respSNA was at least two-fold larger [area under the curve (AUC), sSNA: 7.8 ± 1.1 vs. 3.4 ± 0.7 μV s, rSNA: 11.5 ± 3 vs. 4.8 ± 0.7 μV s, LPK vs. Lewis, both P < 0.05]. Mild hypoxia produced a larger pressure response in LPK [Δ mean arterial pressure (MAP) 30 ± 6 vs. 12 ± 6 mmHg] and augmented respSNA (ΔAUC, sSNA: 8.9 ± 3.4 vs. 2 ± 0.7 μV s, rSNA: 6.1 ± 1.2 vs. 3.1 ± 0.7 μV s, LPK vs. Lewis, all P ≤ 0.05). In contrast, central chemoreceptor stimulation produced comparable changes in blood pressure and respSNA (ΔMAP 13 ± 3 vs. 9 ± 5 mmHg; respSNA ΔAUC, sSNA: 2.5 ± 1 vs. 1.3 ± 0.7 μV s, rSNA: 4.2 ± 0.9 vs. 3.5 ± 1.4 μV s, LPK vs. Lewis, all P > 0.05). These results demonstrate that female rats with CKD exhibit heightened respSNA coupling at baseline that is further augmented by mild hypoxia, and not by hypercapnia. This mechanism may be a contributing driver of hypertension in this animal model of CKD.
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Affiliation(s)
- Manash Saha
- Department of Biomedical Sciences, Macquarie University, Sydney, NSW, Australia.,Department of Nephrology, National Institute of Kidney Disease and Urology, Dhaka, Bangladesh.,Graduate School of Medicine, Wollongong University, Wollongong, NSW, Australia
| | - Qi-Jian Sun
- Department of Biomedical Sciences, Macquarie University, Sydney, NSW, Australia
| | - Cara M Hildreth
- Department of Biomedical Sciences, Macquarie University, Sydney, NSW, Australia
| | - Peter G R Burke
- Department of Biomedical Sciences, Macquarie University, Sydney, NSW, Australia.,Neuroscience Research Australia, Sydney, NSW, Australia
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Salman IM, Ameer OZ, McMurray S, Giarola AS, Sridhar A, Lewis SJ, Hsieh YH. Laterality Influences Central Integration of Baroreceptor Afferent Input in Male and Female Sprague Dawley Rats. Front Physiol 2020; 11:499. [PMID: 32536876 PMCID: PMC7269127 DOI: 10.3389/fphys.2020.00499] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 04/23/2020] [Indexed: 12/02/2022] Open
Abstract
We explored the effects of baroreceptor afferents laterality and sexual dimorphism on the expression of cardiovascular reflex responses to baroreflex activation in Sprague Dawley (SD) rats. Under urethane anesthesia, rats of either sex (total n = 18) were instrumented for left, right and bilateral aortic depressor nerve (ADN) stimulation (1–40 Hz, 0.2 ms, 0.4 mA for 20 s) and measurement of mean arterial pressure (MAP), heart rate (HR) and mesenteric (MVR) and femoral (FVR) vascular resistance. Female rats were matched for the diestrus phase of the estrus cycle. Left, right and bilateral ADN stimulation evoked frequency-dependent drops in MAP, HR, and MVR, and increases in FVR. Irrespective of sex, left and bilateral ADN stimulation as compared to right-sided stimulation mediated greater reflex reductions in MAP, HR, and MVR but not in FVR. In males, reflex bradycardic responses were greater in response to bilateral stimulation relative to both left- and right-sided stimulation. In females, left ADN stimulation evoked the largest increase in FVR. Left and bilateral ADN stimulations evoked greater reductions in MAP and MVR while left-sided stimulation produced larger increases in FVR in females compared with males. All other reflex responses to ADN stimulation were relatively comparable between males and females. These results show a differential baroreflex processing of afferent neurotransmission promoted by left versus right baroreceptor afferent inputs and sexual dimorphism in the expression of baroreflex responses in rats of either sex. Collectively, these data add to our understanding of physiological mechanisms pertaining to baroreflex control in both males and females.
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Affiliation(s)
- Ibrahim M Salman
- College of Pharmacy, Alfaisal University, Riyadh, Saudi Arabia.,Division of Pulmonology, Allergy and Immunology, Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Omar Z Ameer
- College of Pharmacy, Alfaisal University, Riyadh, Saudi Arabia
| | - Sheridan McMurray
- Department of Disease Biology, Galvani Bioelectronics, Hertfordshire, United Kingdom
| | - Alessandra S Giarola
- Department of Disease Biology, Galvani Bioelectronics, Hertfordshire, United Kingdom
| | - Arun Sridhar
- Department of Disease Biology, Galvani Bioelectronics, Hertfordshire, United Kingdom
| | - Stephen J Lewis
- Division of Pulmonology, Allergy and Immunology, Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Yee-Hsee Hsieh
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
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10
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Soyalp C, Kocak MN, Ahiskalioglu A, Aksoy M, Atalay C, Aydin MD, Cakir M, Calikoglu C, Ozmen S. New determinants for casual peripheral mechanism of neurogenic lung edema in subarachnoid hemorrhage due to ischemic degeneration of vagal nerve, kidney and lung circuitry. Experimental study1. Acta Cir Bras 2019; 34:e201900303. [PMID: 30892389 PMCID: PMC6585894 DOI: 10.1590/s0102-865020190030000003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 02/10/2019] [Indexed: 01/13/2023] Open
Abstract
Purpose To evaluate whether there is a relationship between renal artery vasospasm
related low glomerular density or degeneration and neurogenic lung edema
(NLE) following subarachnoid hemorrhage. Methods This study was conducted on 26 rabbits. A control group was formed of five
animals, a SHAM group of 5 to which saline and a study group (n=16) injected
with homologous blood into the sylvian cisterna. Numbers of degenerated
axons of renal branches of vagal nerves, atrophic glomerulus numbers and NLE
scores were recorded. Results Important vagal degeneration, severe renal artery vasospasm, intrarenal
hemorrhage and glomerular atrophy observed in high score NLE detected
animals. The mean degenerated axon density of vagal nerves
(n/mm2), atrophic glomerulus density (n/mm3) and NLE
scores of control, SHAM and study groups were estimated as 2.40±1.82,
2.20±1.30, 1.80±1.10, 8.00±2.24, 8.80±2.39, 4.40±1.14 and 154.38±13.61,
34.69±2.68 and 12.19±1.97 consecutively. Degenerated vagal axon, atrophic
glomerulus and NLE scores are higher in study group than other groups and
the differences are statistically meaningful (p<0.001). Conclusion Vagal complex degeneration based glomerular atrophy have important roles on
NLE following SAH which has not been extensively mentioned in the
literature.
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Affiliation(s)
- Celaleddin Soyalp
- MD, Department of Anesthesiology, Medical Faculty, Yil University, Van, Turkey. Conception and design of the study, acquisition of data, manuscript writing
| | - Mehmet Nuri Kocak
- MD, Department of Neurology, Medical Faculty, Ataturk University, Erzurum, Turkey. Technical procedures, manuscript preparation
| | - Ali Ahiskalioglu
- Assistant Prof., Department of Anesthesiology and Reanimation, Medical Faculty, Ataturk University, Erzurum, Turkey. Acquisition, analysis and interpretation of data; manuscript preparation; critical revision
| | - Mehmet Aksoy
- Assistant Prof., Department of Anesthesiology and Reanimation, Medical Faculty, Ataturk University, Erzurum, Turkey. Acquisition, analysis and interpretation of data; manuscript preparation; critical revision
| | - Canan Atalay
- Assistant Prof., Department of Anesthesiology and Reanimation, Medical Faculty, Ataturk University, Erzurum, Turkey. Acquisition, analysis and interpretation of data; manuscript preparation; critical revision
| | - Mehmet Dumlu Aydin
- Prof., Department of Neurosurgery, Medical Faculty, Ataturk University, Erzurum, Turkey. Histopathological examinations, manuscript writing, critical revision, final approval
| | - Murteza Cakir
- Prof., Department of Neurosurgery, Medical Faculty, Ataturk University, Erzurum, Turkey. Histopathological examinations, manuscript writing, critical revision, final approval
| | - Cagatay Calikoglu
- Prof., Department of Neurosurgery, Medical Faculty, Ataturk University, Erzurum, Turkey. Histopathological examinations, manuscript writing, critical revision, final approval
| | - Sevilay Ozmen
- MD, Department of Pathology, Medical Faculty, Ataturk University, Erzurum, Turkey. Histopathological examinations
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11
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Increased excitatory regulation of the hypothalamic paraventricular nucleus and circulating vasopressin results in the hypertension observed in polycystic kidney disease. J Hypertens 2019; 37:109-115. [DOI: 10.1097/hjh.0000000000001841] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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12
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Underwood CF, Hildreth CM, Wyse BF, Boyd R, Goodchild AK, Phillips JK. Uraemia: an unrecognized driver of central neurohumoral dysfunction in chronic kidney disease? Acta Physiol (Oxf) 2017; 219:305-323. [PMID: 27247097 DOI: 10.1111/apha.12727] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 01/21/2016] [Accepted: 05/31/2016] [Indexed: 12/12/2022]
Abstract
Chronic kidney disease (CKD) carries a large cardiovascular burden in part due to hypertension and neurohumoral dysfunction - manifesting as sympathetic overactivity, baroreflex dysfunction and chronically elevated circulating vasopressin. Alterations within the central nervous system (CNS) are necessary for the expression of neurohumoral dysfunction in CKD; however, the underlying mechanisms are poorly defined. Uraemic toxins are a diverse group of compounds that accumulate as a direct result of renal disease and drive dysfunction in multiple organs, including the brain. Intensive haemodialysis improves both sympathetic overactivity and cardiac baroreflex sensitivity in renal failure patients, indicating that uraemic toxins participate in the maintenance of autonomic dysfunction in CKD. In rodents exposed to uraemia, immediate early gene expression analysis suggests upregulated activity of not only pre-sympathetic but also vasopressin-secretory nuclei. We outline several potential mechanisms by which uraemia might drive neurohumoral dysfunction in CKD. These include superoxide-dependent effects on neural activity, depletion of nitric oxide and induction of low-grade systemic inflammation. Recent evidence has highlighted superoxide production as an intermediate for the depolarizing effect of some uraemic toxins on neuronal cells. We provide preliminary data indicating augmented superoxide production within the hypothalamic paraventricular nucleus in the Lewis polycystic kidney rat, which might be important for mediating the neurohumoral dysfunction exhibited in this CKD model. We speculate that the uraemic state might serve to sensitize the central actions of other sympathoexcitatory factors, including renal afferent nerve inputs to the CNS and angiotensin II, by way of recruiting convergent superoxide-dependent and pro-inflammatory pathways.
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Affiliation(s)
- C. F. Underwood
- Department of Biomedical Sciences; Macquarie University; Sydney NSW Australia
| | - C. M. Hildreth
- Department of Biomedical Sciences; Macquarie University; Sydney NSW Australia
| | - B. F. Wyse
- Department of Biomedical Sciences; Macquarie University; Sydney NSW Australia
| | - R. Boyd
- Department of Biomedical Sciences; Macquarie University; Sydney NSW Australia
| | - A. K. Goodchild
- Department of Biomedical Sciences; Macquarie University; Sydney NSW Australia
| | - J. K. Phillips
- Department of Biomedical Sciences; Macquarie University; Sydney NSW Australia
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Salman IM, Hildreth CM, Phillips JK. Chronic kidney disease impairs renal nerve and haemodynamic reflex responses to vagal afferent input through a central mechanism. Auton Neurosci 2016; 204:65-73. [PMID: 27776979 DOI: 10.1016/j.autneu.2016.10.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 09/20/2016] [Accepted: 10/08/2016] [Indexed: 11/25/2022]
Abstract
We investigated age- and sex-related changes in reflex renal sympathetic nerve activity (RSNA) and haemodynamic responses to vagal afferent stimulation in a rodent model of chronic kidney disease (CKD). Using anaesthetised juvenile (7-8weeks) and adult (12-13weeks) Lewis Polycystic Kidney (LPK) and Lewis control rats of either sex (n=63 total), reflex changes in RSNA, heart rate (HR) and mean arterial pressure (MAP) to vagal afferent stimulation (5-s train, 4.0V, 2.0-ms pulses, 1-16Hz) were measured. In all groups, stimulation of the vagal afferents below 16Hz produced frequency-dependent reductions in RSNA, HR and MAP, while a 16Hz stimulus produced an initial sympathoinhibition followed by sympathoexcitation. In juvenile LPK versus age-matched Lewis, sympathoinhibition was reduced when responses were expressed as % baseline (P<0.05), but not as microvolts, while bradycardic responses were greater. Reflex depressor responses were greater (P=0.015) only in juvenile female LPK. In adult LPK, reflex sympathoinhibition (%) was blunted (P<0.05), and an age-related decline apparent (when expressed as microvolts). Reflex reductions in HR and MAP were only diminished (P<0.05) in adult female LPK versus age-matched Lewis. Peak reflex sympathoexcitation at 16Hz did not differ between groups; however, area under the curve values were greater in the LPK versus Lewis (overall, 9±1 versus 19±3μVs, P<0.05) irrespective of age, suggestive of enhanced sympathoexcitatory drive in the LPK. Our data demonstrates a progressive deficit in the central processing of vagal afferent input and a differential sex influence on reflex regulation of autonomic function and blood pressure homeostasis in CKD.
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Affiliation(s)
- Ibrahim M Salman
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia.
| | - Cara M Hildreth
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Jacqueline K Phillips
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
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14
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Salman IM. Current Approaches to Quantifying Tonic and Reflex Autonomic Outflows Controlling Cardiovascular Function in Humans and Experimental Animals. Curr Hypertens Rep 2016; 17:84. [PMID: 26363932 DOI: 10.1007/s11906-015-0597-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The role of the autonomic nervous system in the pathophysiology of human and experimental models of cardiovascular disease is well established. In the recent years, there have been some rapid developments in the diagnostic approaches used to assess and monitor autonomic functions. Although most of these methods are devoted for research purposes in laboratory animals, many have still found their way to routine clinical practice. To name a few, direct long-term telemetry recording of sympathetic nerve activity (SNA) in rodents, single-unit SNA recording using microneurography in human subjects and spectral analysis of blood pressure and heart rate in both humans and animals have recently received an overwhelming attention. In this article, we therefore provide an overview of the methods and techniques used to assess tonic and reflex autonomic functions in humans and experimental animals, highlighting current advances available and procedure description, limitations and usefulness for diagnostic purposes.
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Affiliation(s)
- Ibrahim M Salman
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia.
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15
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Major Autonomic Neuroregulatory Pathways Underlying Short- and Long-Term Control of Cardiovascular Function. Curr Hypertens Rep 2016; 18:18. [DOI: 10.1007/s11906-016-0625-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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16
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Salman IM. Cardiovascular Autonomic Dysfunction in Chronic Kidney Disease: a Comprehensive Review. Curr Hypertens Rep 2016; 17:59. [PMID: 26071764 DOI: 10.1007/s11906-015-0571-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Cardiovascular autonomic dysfunction is a major complication of chronic kidney disease (CKD), likely contributing to the high incidence of cardiovascular mortality in this patient population. In addition to adrenergic overdrive in affected individuals, clinical and experimental evidence now strongly indicates the presence of impaired reflex control of both sympathetic and parasympathetic outflow to the heart and vasculature. Although the principal underlying mechanisms are not completely understood, potential involvements of altered baroreceptor, cardiopulmonary, and chemoreceptor reflex function, along with factors including but not limited to increased renin-angiotensin-aldosterone system activity, activation of the renal afferents and cardiovascular structural remodeling have been suggested. This review therefore analyzes potential mechanisms underpinning autonomic imbalance in CKD, covers results accumulated thus far on cardiovascular autonomic function studies in clinical and experimental renal failure, discusses the role of current interventional and therapeutic strategies in ameliorating autonomic deficits associated with chronic renal dysfunction, and identifies gaps in our knowledge of neural mechanisms driving cardiovascular disease in CKD.
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Affiliation(s)
- Ibrahim M Salman
- The Australian School of Advanced Medicine, Macquarie University, Sydney, New South Wales, Australia,
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Kaur M, Chandran DS, Jaryal AK, Bhowmik D, Agarwal SK, Deepak KK. Baroreflex dysfunction in chronic kidney disease. World J Nephrol 2016; 5:53-65. [PMID: 26788464 PMCID: PMC4707168 DOI: 10.5527/wjn.v5.i1.53] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2015] [Revised: 10/04/2015] [Accepted: 11/25/2015] [Indexed: 02/06/2023] Open
Abstract
Chronic kidney disease (CKD) patients have high cardiovascular mortality and morbidity. The presence of traditional and CKD related risk factors results in exaggerated vascular calcification in these patients. Vascular calcification is associated with reduced large arterial compliance and thus impaired baroreflex sensitivity (BRS) resulting in augmented blood pressure (BP) variability and hampered BP regulation. Baroreflex plays a vital role in short term regulation of BP. This review discusses the normal baroreflex physiology, methods to assess baroreflex function, its determinants along with the prognostic significance of assessing BRS in CKD patients, available literature on BRS in CKD patients and the probable patho-physiology of baroreflex dysfunction in CKD.
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Salman IM, Sarma Kandukuri D, Harrison JL, Hildreth CM, Phillips JK. Direct conscious telemetry recordings demonstrate increased renal sympathetic nerve activity in rats with chronic kidney disease. Front Physiol 2015; 6:218. [PMID: 26300784 PMCID: PMC4523722 DOI: 10.3389/fphys.2015.00218] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 07/20/2015] [Indexed: 01/05/2023] Open
Abstract
Chronic kidney disease (CKD) is associated with sympathetic hyperactivity and impaired blood pressure control reflex responses, yet direct evidence demonstrating these features of autonomic dysfunction in conscious animals is still lacking. Here we measured renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) using telemetry-based recordings in a rat model of CKD, the Lewis Polycystic Kidney (LPK) rat, and assessed responses to chemoreflex activation and acute stress. Male LPK and Lewis control animals (total n = 16) were instrumented for telemetric recording of RSNA and MAP. At 12–13 weeks-of-age, resting RSNA and MAP, sympathetic and haemodynamic responses to both peripheral (hypoxia: 10% O2) and central chemoreflex (hypercapnia: 7% CO2) activation and acute stress (open-field exposure), were measured. As indicators of renal function, urinary protein (UPro) and creatinine (UCr) levels were assessed. LPK rats had higher resting RSNA (1.2 ± 0.1 vs. 0.6 ± 0.1 μV, p < 0.05) and MAP (151 ± 8 vs. 97 ± 2 mmHg, p < 0.05) compared to Lewis. MAP was negatively correlated with UCr (r = −0.80, p = 0.002) and positively correlated with RSNA (r = 0.66, p = 0.014), with multiple linear regression modeling indicating the strongest correlation was with Ucr. RSNA and MAP responses to activation of the central chemoreflex and open-field stress were reduced in the LPK relative to the Lewis (all p < 0.05). This is the first description of dual conscious telemetry recording of RSNA and MAP in a genetic rodent model of CKD. Elevated RSNA is likely a key contributor to the marked hypertension in this model, while attenuated RSNA and MAP responses to central chemoreflex activation and acute stress in the LPK indicate possible deficits in the neural processing of autonomic outflows evoked by these sympathoexcitatory pathways.
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Affiliation(s)
- Ibrahim M Salman
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University Sydney, NSW, Australia
| | - Divya Sarma Kandukuri
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University Sydney, NSW, Australia
| | - Joanne L Harrison
- School of Veterinary and Life Sciences, Murdoch University Murdoch, WA, Australia
| | - Cara M Hildreth
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University Sydney, NSW, Australia
| | - Jacqueline K Phillips
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University Sydney, NSW, Australia
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