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Kawada T, Yamamoto H, Yokoi A, Nishiura A, Kakuuchi M, Yokota S, Matsushita H, Alexander J, Saku K. Acute effects of empagliflozin on open-loop baroreflex function and urine glucose excretion in Goto-Kakizaki diabetic rats. J Physiol Sci 2023; 73:7. [PMID: 37046217 DOI: 10.1186/s12576-023-00861-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 03/17/2023] [Indexed: 04/14/2023]
Abstract
Although suppression of sympathetic activity is suggested as one of the underlying mechanisms for the cardioprotective effects afforded by sodium-glucose cotransporter 2 (SGLT2) inhibitors, whether the modulation of glucose handling acutely affects sympathetic regulation of arterial pressure remains to be elucidated. In Goto-Kakizaki diabetic rats, we estimated the open-loop static characteristics of the carotid sinus baroreflex together with urine glucose excretion using repeated 11-min step input sequences. After the completion of the 2nd sequence, an SGLT2 inhibitor empagliflozin (10 mg kg-1) or vehicle solution was administered intravenously (n = 7 rats each). Empagliflozin did not significantly affect the baroreflex neural or peripheral arc, despite significantly increasing urine glucose excretion (from 0.365 ± 0.216 to 8.514 ± 0.864 mg·min-1·kg-1, P < 0.001) in the 7th and 8th sequences. The possible sympathoinhibitory effect of empagliflozin may be an indirect effect associated with chronic improvements in renal energy status and general disease conditions.
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Affiliation(s)
- Toru Kawada
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, 564-8565, Japan.
| | - Hiromi Yamamoto
- Department of Cardiovascular Medicine, Kurashiki Central Hospital, Ohara HealthCare Foundation, Okayama, 710-8602, Japan
| | - Aimi Yokoi
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, 564-8565, Japan
| | - Akitsugu Nishiura
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, 564-8565, Japan
| | - Midori Kakuuchi
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, 564-8565, Japan
| | - Shohei Yokota
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, 564-8565, Japan
| | - Hiroki Matsushita
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, 564-8565, Japan
| | - Joe Alexander
- Medical and Health Informatics, NTT Research, Inc., Sunnyvale, CA, 94085, USA
| | - Keita Saku
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, 564-8565, Japan
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Roles of sleep-related cardiovascular autonomic functions in voluntary-exercise-induced alleviation of hypertension in spontaneously hypertensive rats. Hypertens Res 2022; 45:1154-1167. [PMID: 35459851 DOI: 10.1038/s41440-022-00916-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 03/03/2022] [Accepted: 03/08/2022] [Indexed: 12/12/2022]
Abstract
Autonomic dysfunction and sleep problems are closely associated with hypertension and predict cardiovascular morbidity and mortality. Animal studies and clinical observations have identified exercise as an important factor in preventing and treating hypertension. However, the roles of autonomic function and sleep in the antihypertensive mechanisms of exercise are still not fully understood. This study aimed to clarify the physiological mechanisms associated with autonomic function and sleep through wheel exercise. Male spontaneously hypertensive rats (SHRs) were grouped into a wheel-exercised group and a sedentary group (controls). Electroencephalogram, electromyogram, electrocardiogram, and mean arterial pressure (MAP) were recorded simultaneously for 24 h once a week over 11 weeks. Wheel exercise was initiated in the SHRs at 12 weeks old and continued for another eight weeks. A significant suppression in the age-related elevation of MAP was noted in the SHRs undergoing wheel exercise. The reduction in MAP was correlated with increased parasympathetic activity and baroreflex sensitivity and decreased sympathetic activity, mainly during quiet sleep. Exercise increased the paradoxical sleep time and theta power (associated with cognitive function) but not the delta power (an indicator of sleep depth) or the attenuation of circadian rhythm flattening (characterized by increased wakefulness and less sleep during the light period and the opposite during the dark period). Furthermore, the exercise-induced changes in autonomic function occurred before those in sleep patterns, which were dependent on each other. In conclusion, wheel exercise can modulate sleep-related cardiovascular dysfunction and the flattening of circadian rhythm, preventing the progression of hypertension, which reduces the incidence of cardiovascular diseases.
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Kawada T, Saku K, Miyamoto T. Closed-Loop Identification of Baroreflex Properties in the Frequency Domain. Front Neurosci 2021; 15:694512. [PMID: 34526878 PMCID: PMC8435638 DOI: 10.3389/fnins.2021.694512] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 07/26/2021] [Indexed: 11/13/2022] Open
Abstract
The arterial baroreflex system plays a key role in maintaining the homeostasis of arterial pressure (AP). Changes in AP affect autonomic nervous activities through the baroreflex neural arc, whereas changes in the autonomic nervous activities, in turn, alter AP through the baroreflex peripheral arc. This closed-loop negative feedback operation makes it difficult to identify open-loop dynamic characteristics of the neural and peripheral arcs. Regarding sympathetic AP controls, we examined the applicability of a nonparametric frequency-domain closed-loop identification method to the carotid sinus baroreflex system in anesthetized rabbits. This article compares the results of an open-loop analysis applied to open-loop data, an open-loop analysis erroneously applied to closed-loop data, and a closed-loop analysis applied to closed-loop data. To facilitate the understanding of the analytical method, sample data files and sample analytical codes were provided. In the closed-loop identification, properties of the unknown central noise that modulated the sympathetic nerve activity and the unknown peripheral noise that fluctuated AP affected the accuracy of the estimation results. A priori knowledge about the open-loop dynamic characteristics of the arterial baroreflex system may be used to advance the assessment of baroreflex function under closed-loop conditions in the future.
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Affiliation(s)
- Toru Kawada
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Keita Saku
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Tadayoshi Miyamoto
- Department of Sport and Health Sciences, Faculty of Sport and Health Sciences, Osaka Sangyo University, Osaka, Japan
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Bezerra LS, Magnani M, Pimentel TC, Freire FMDS, da Silva TAF, Ramalho RC, Alves AF, de Brito Alves JL, de Medeiros IA, Veras RC. Carboxymethyl-glucan from Saccharomyces cerevisiae reduces blood pressure and improves baroreflex sensitivity in spontaneously hypertensive rats. Food Funct 2021; 12:8552-8560. [PMID: 34337642 DOI: 10.1039/d1fo01079d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Carboxymethyl-glucan (CMG) is a derivative of β-d-glucan extracted from Sacharomyces cerevisae. This polymer presents improved physicochemical properties and shows health benefits, such as immunomodulation, antioxidant, anti-inflammatory, anti-tumor, and antiplatelet activities, and improved vascular function. However, studies concerning the effect of administration of CMG on the cardiovascular parameters, mainly in the field of hypertension, are scarce. This study aimed to investigate the effect of administration of CMG in spontaneously hypertensive rats (SHR) and normotensive rats (WKY) models. Normotensive and hypertensive animals received CMG at doses of 20 mg kg-1 and 60 mg kg-1 for four weeks. Then, weight gain, lipid profile, renal function, blood pressure, cardiac hypertrophy, baroreflex sensitivity, and sympathetic tone were evaluated. Oral administration of CMG influenced weight gain and cholesterol levels, and significantly reduced urea in the hypertensive animals. It decreased blood pressure levels and cardiac hypertrophy, improved baroreflex response, and reduced the influence of sympathetic tone. The results demonstrate the antihypertensive effect of CMG through improvement in baroreflex sensitivity via sympathetic tone modulation.
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Affiliation(s)
- Lorena Soares Bezerra
- Post-Graduate Program in Nutritional Sciences, Health Sciences Center, Federal University of Paraíba (Universidade Federal da Paraíba - UFPB), Brazil.
| | - Marciane Magnani
- Post-Graduate Program in Nutritional Sciences, Health Sciences Center, Federal University of Paraíba (Universidade Federal da Paraíba - UFPB), Brazil. and Department of Food Engineering, Federal University of Paraíba (UFPB), Brazil
| | | | | | | | | | - Adriano Francisco Alves
- Department of Physiology and Pathology, Laboratory of Pathology, Health Sciences Center, UFPB, Brazil
| | - José Luiz de Brito Alves
- Post-Graduate Program in Nutritional Sciences, Health Sciences Center, Federal University of Paraíba (Universidade Federal da Paraíba - UFPB), Brazil.
| | - Isac Almeida de Medeiros
- Post-Graduate Program in Natural and Synthetic Bioactive Products, Health Sciences Center, UFPB, Brazil
| | - Robson Cavalcante Veras
- Post-Graduate Program in Nutritional Sciences, Health Sciences Center, Federal University of Paraíba (Universidade Federal da Paraíba - UFPB), Brazil. and Department of Pharmaceutical Sciences, Health Sciences Center, UFPB, Brazil
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Kawada T, Nishikawa T, Suehara S, Sawada S, Tanaka T, Uenohara M, Yamamoto H, Sugimachi M. Open-loop analysis on sympathetically mediated arterial pressure and urine output responses in spontaneously hypertensive rats: effect of renal denervation. J Physiol Sci 2021; 71:13. [PMID: 33879059 PMCID: PMC10717997 DOI: 10.1186/s12576-021-00798-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 03/31/2021] [Indexed: 12/12/2022]
Abstract
Primary acute sympathetic activation (PASA) causes a subsequent arterial pressure (AP) elevation. In this case, an antidiuretic effect via the renal innervation and pressure diuresis can act antagonistically on the kidneys. We examined the effect of PASA on urine output in spontaneously hypertensive rats (SHR) 4-7 days after unilateral renal denervation (RDN) (n = 9). The slope of the plot of urine flow versus AP was positive (0.120 ± 0.031 μL min-1 kg-1 mmHg-1) on the intact side, but it was less than 1/3 of the slope observed previously in normotensive Wistar-Kyoto rats (WKY). RDN did not normalize the slope of urine flow versus AP (0.179 ± 0.025 μL min-1 kg-1 mmHg-1, P = 0.098 versus the intact side). The urine flow at the operating point of the AP tended to be greater on the denervated than the intact side (29.0 ± 1.8 vs. 25.3 ± 1.9 μL min-1 kg-1, P = 0.055). The percent increase (17.2 ± 7.2%) was not different from that observed previously in WKY. Although high-resting sympathetic nerve activity is prerequisite for maintaining hypertension in SHR, the effect of sympathetic innervation on the urine output function was not greater than that in WKY.
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Affiliation(s)
- Toru Kawada
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, 564-8565, Japan.
| | - Takuya Nishikawa
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, 564-8565, Japan
| | - Satoru Suehara
- Corporate R&D Center, Terumo Corporation, Kanagawa, 259-0151, Japan
| | - Satoshi Sawada
- Corporate R&D Center, Terumo Corporation, Kanagawa, 259-0151, Japan
| | - Tetsuo Tanaka
- Corporate R&D Center, Terumo Corporation, Kanagawa, 259-0151, Japan
| | - Minako Uenohara
- Corporate R&D Center, Terumo Corporation, Kanagawa, 259-0151, Japan
| | - Hiromi Yamamoto
- Department of Cardiology, Kurashiki Central Hospital, Ohara HealthCare Foundation, Okayama, 710-8602, Japan
| | - Masaru Sugimachi
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, 564-8565, Japan
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Han W, Wang M, Zhai X, Gan Q, Guan S, Qu X. Chemical renal denervation-induced upregulation of the ACE2/Ang (1-7)/Mas axis attenuates blood pressure elevation in spontaneously hypertensive rats. Clin Exp Hypertens 2020; 42:661-668. [PMID: 32476477 DOI: 10.1080/10641963.2020.1772812] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Wenzheng Han
- Department of Cardiology, Huadong Hospital Affiliated to Fudan University , Shanghai, China
- Shanghai Key Laboratory of Clinical Geriatric Medicine , Shanghai, China
| | - Ming Wang
- Department of Cardiology, Huadong Hospital Affiliated to Fudan University , Shanghai, China
| | - Xinrong Zhai
- Department of Cardiology, Huadong Hospital Affiliated to Fudan University , Shanghai, China
| | - Qian Gan
- Department of Cardiology, Huadong Hospital Affiliated to Fudan University , Shanghai, China
| | - Shaofeng Guan
- Department of Cardiology, Huadong Hospital Affiliated to Fudan University , Shanghai, China
- Shanghai Key Laboratory of Clinical Geriatric Medicine , Shanghai, China
| | - Xinkai Qu
- Department of Cardiology, Huadong Hospital Affiliated to Fudan University , Shanghai, China
- Shanghai Key Laboratory of Clinical Geriatric Medicine , Shanghai, China
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Sata Y, Marques FZ, Kaye DM. The Emerging Role of Gut Dysbiosis in Cardio-metabolic Risk Factors for Heart Failure. Curr Hypertens Rep 2020; 22:38. [DOI: 10.1007/s11906-020-01046-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Nakahara H, Kawada T, Ueda SY, Kawai E, Yamamoto H, Sugimachi M, Miyamoto T. Acupoint dependence of depressor and bradycardic responses elicited by manual acupuncture stimulation in humans. J Physiol Sci 2019; 69:1077-1084. [PMID: 31707634 PMCID: PMC10717143 DOI: 10.1007/s12576-019-00728-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 10/29/2019] [Indexed: 02/04/2023]
Abstract
The cardiovascular effects of the autonomic nervous system (ANS) are modulated by inputs from peripheral sensors and other brain regions. However, it currently remains unknown whether the manual acupuncture (MA) stimulation of different acupuncture points evokes different responses by the heart and vasculature, a phenomenon known as "site specificity". Sixty healthy subjects were randomly divided into a control group and MA stimulation groups at the lower leg, ear, abdomen, and forearm. MA was performed at 1 Hz for 2 min. A depressor response was observed only in the lower leg stimulation group, in which mean blood pressure significantly decreased from 83.4 ± 10.1 to 80.9 ± 11.7 mmHg (p < 0.003). A bradycardic response was elicited in all MA stimulation groups. There was no significant differences in the magnitude of the bradycardic response between groups. MA-induced cardiovascular responses, which may be mediated by the modulation of ANS, differ depending on acupuncture points.
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Affiliation(s)
- Hidehiro Nakahara
- Graduate School of Health Sciences, Morinomiya University of Medical Sciences, 1-26-16 Nankokita, Suminoe, Osaka, 559-8611, Japan.
| | - Toru Kawada
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, 6-1 Kishibe-Shimmachi, Suita, Osaka, 564-8565, Japan
| | - Shin-Ya Ueda
- Department of Physical Education, Faculty of Education, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan
| | - Eriko Kawai
- Osaka City University Graduate School of Medicine, 3-3-138 Sugimoto Sumiyoshi, Osaka, 558-8585, Japan
| | - Hiromi Yamamoto
- Division of Cardiology, Department of Medicine, Faculty of Medicine, Kindai University, 377-2 Ohno-higashi, Sayama, Osaka, 589-8511, Japan
| | - Masaru Sugimachi
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, 6-1 Kishibe-Shimmachi, Suita, Osaka, 564-8565, Japan
| | - Tadayoshi Miyamoto
- Department of Sport and Health Sciences, Faculty of Sport and Health Sciences, Osaka Sangyo University, Wellness 2008, 3-1-1, Nakagaito, Daito, Osaka, 573-1004, Japan
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Ambulatory arterial stiffness index as a predictor of blood pressure response to renal denervation. J Hypertens 2019; 36:1414-1422. [PMID: 29465712 DOI: 10.1097/hjh.0000000000001682] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Renal denervation (RDN) can reduce blood pressure (BP) in patients with resistant hypertension, but less so in patients with isolated systolic hypertension. A possible explanation is that patients with stiffer arteries may have lesser neural contribution to their hypertension. METHOD We hypothesized that arterial stiffness predicts the response to RDN. From ambulatory BP monitoring (ABPM), ambulatory arterial stiffness index (AASI) was calculated as 1 - the regression slope of DBP versus SBP. RESULTS In 111 patients with resistant hypertension, RDN reduced office and 24-h SBP after 3, 6, and 12 months (by -11 ± 22, -11 ± 25, -14 ± 21 mmHg for office, and -4 ± 11, -5 ± 12, -5 ± 15 mmHg for 24-h SBP, respectively, P < 0.01). Patients with baseline AASI above the median (>0.51) showed no change in 24-h SBP at 6 months after RDN (-0.4 ± 12.3 mmHg, P > 0.05), whereas an AASI below 0.51was associated with a marked reduction (-9.3 ± 11.0 mmHg, P < 0.01). Across AASI quartiles, patients in the highest quartile (AASI ≥ 0.60) had lower muscle sympathetic nerve activity than the other three quartiles (39 ± 13 versus 49 ± 13 bursts/min, P = 0.035). The responder rate, defined as a 24-h SBP reduction of at least 5% was 58% in the lowest AASI quartile (<0.45) and 16% in the highest quartile (≥0.60). After adjustment for age, sex, BMI, office and 24-h SBP, an AASI less than 0.51predicted those who respond to RDN (odds ratio 3.46, P = 0.04). CONCLUSION We conclude that in patients with resistant hypertension, a lower AASI is an independent predictor of the BP response to RDN, possibly explained by a more pronounced neurogenic rather than biomechanical contribution to their BP elevation.
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Teng X, Li H, Xue H, Jin S, Xiao L, Guo Q, Wu Y. GABA A receptor, K ATP channel and L-type Ca 2+ channel is associated with facilitation effect of H 2S on the baroreceptor reflex in spontaneous hypertensive rats. Pharmacol Rep 2019; 71:968-975. [PMID: 31470293 DOI: 10.1016/j.pharep.2019.05.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 04/08/2019] [Accepted: 05/14/2019] [Indexed: 12/15/2022]
Abstract
BACKGROUND We aimed to investigate whether the facilitating effect of H2S on the baroreceptor reflex is associated with the GABAA receptor, KATP channel and L-type Ca2+ channel pathway. METHODS Spontaneously hypertensive rats (SHRs) and Wistar Kyoto (WKY) rats were used to investigate the facilitating effect of H2S on the baroreceptor reflex by perfusing the isolated carotid sinus. The mechanism by which H2S facilitated the baroreceptor reflex was determined by using Bay K8644 (an agonist of calcium channels), glibenclamide (Gli, a KATP channel blocker), and picrotoxin (PIC, a blocker of γ-aminobutyric acid [GABA]A receptor). RESULTS As compared with WKY rats, SHRs showed impaired baroreceptor reflex sensitivity, as demonstrated by a right and upward shift of the functional curve for the intrasinus pressure-arterial blood pressure relation. H2S perfusion (25, 50, or 100 μmol/L) dose-dependently ameliorated the impaired sensitivity of the baroreceptor reflex. Bay K8644 (500 nmol/L), Gli (20 μmol/L) and PIC (50 μmol/L) all prevented H2S ameliorating the impaired baroreceptor reflex. CONCLUSIONS H2S facilitating the baroreceptor reflex might be associated with activating the GABAA receptor, opening the KATP channel, and closing the L-type Ca2+ channel. These areas should provide new targets for preventing and treating hypertension.
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Affiliation(s)
- Xu Teng
- Department of Physiology, Institute of Basic Medicine, Hebei Medical University, Shijiazhuang, China; Hebei Key Lab of Laboratory Animal Science, Hebei Medical University, Shijiazhuang, China
| | - Hui Li
- Department of Physiology, Institute of Basic Medicine, Hebei Medical University, Shijiazhuang, China
| | - Hongmei Xue
- Department of Physiology, Institute of Basic Medicine, Hebei Medical University, Shijiazhuang, China
| | - Sheng Jin
- Department of Physiology, Institute of Basic Medicine, Hebei Medical University, Shijiazhuang, China
| | - Lin Xiao
- Department of Physiology, Institute of Basic Medicine, Hebei Medical University, Shijiazhuang, China; Hebei Key Lab of Laboratory Animal Science, Hebei Medical University, Shijiazhuang, China
| | - Qi Guo
- Department of Physiology, Institute of Basic Medicine, Hebei Medical University, Shijiazhuang, China
| | - Yuming Wu
- Department of Physiology, Institute of Basic Medicine, Hebei Medical University, Shijiazhuang, China; Key Laboratory of Vascular Medicine of Hebei Province, Shijiazhuang, China; Hebei Collaborative Innovation Center for Cardio-Cerebrovascular Disease, Shijiazhuang, China.
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Kawada T, Hayama Y, Nishikawa T, Yamamoto H, Tanaka K, Sugimachi M. Even weak vasoconstriction from rilmenidine can be unmasked in vivo by opening the baroreflex feedback loop. Life Sci 2019; 219:144-151. [PMID: 30630007 DOI: 10.1016/j.lfs.2019.01.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 01/05/2019] [Accepted: 01/07/2019] [Indexed: 11/17/2022]
Abstract
AIMS Rilmenidine and moxonidine are centrally acting antihypertensive agents that are more selective for I1-imidazoline receptors than for α2-adrenergic receptors. Moxonidine previously showed a peripheral vasoconstrictive effect stronger than generally recognized, which counteracted an arterial pressure (AP) lowering effect resulting from central sympathoinhibition. We tested whether rilmenidine also showed a significant vasoconstrictive effect that could attenuate its AP lowering effect. MAIN METHODS Efferent sympathetic nerve activity (SNA) and AP responses to changes in carotid sinus pressure were compared in nine anesthetized Wistar-Kyoto rats before and after low, medium, and high doses (40, 100, and 250 μg/kg, respectively) of intravenous rilmenidine. KEY FINDINGS High-dose rilmenidine narrowed the range of the SNA response (from 89.6 ± 2.9% to 50.4 ± 7.9%, P < 0.001) and reduced the lower asymptote of SNA (from 13.5 ± 3.0% to 2.7 ± 1.5%, P < 0.001). High-dose rilmenidine significantly increased the intercept (from 57.1 ± 3.8 to 78.2 ± 2.7 mm Hg, P < 0.001) but reduced the slope (from 0.82 ± 0.08 to 0.51 ± 0.07 mm Hg/%, P < 0.001) of the SNA-AP relationship. The reduction in the operating-point AP induced by high-dose rilmenidine did not significantly differ based on whether the peripheral effect was considered (-19.8 ± 2.2 vs. -26.4 ± 5.3 mm Hg, not significant). SIGNIFICANCE Rilmenidine increased AP in the absence of SNA, which suggests a peripheral vasoconstrictive effect; however, the vasoconstrictive effect was weak and did not significantly counteract the AP-lowering effect through central sympathoinhibition.
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Affiliation(s)
- Toru Kawada
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka 565-8565, Japan.
| | - Yohsuke Hayama
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka 565-8565, Japan
| | - Takuya Nishikawa
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka 565-8565, Japan
| | - Hiromi Yamamoto
- Division of Cardiology, Department of Medicine, Faculty of Medicine, Kindai University, Osaka 589-8511, Japan
| | - Kunihiko Tanaka
- Graduate School of Health and Medicine, Gifu University of Medical Science, Gifu 501-3892, Japan
| | - Masaru Sugimachi
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka 565-8565, Japan
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Central activation of cardiac vagal nerve by α 2-adrenergic stimulation is impaired in streptozotocin-induced type 1 diabetic rats. Auton Neurosci 2018; 216:39-45. [PMID: 30220605 DOI: 10.1016/j.autneu.2018.09.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 08/06/2018] [Accepted: 09/06/2018] [Indexed: 02/06/2023]
Abstract
To elucidate the abnormality of cardiac vagal control in streptozotocin-induced type 1 diabetic rats, we measured left ventricular myocardial interstitial acetylcholine (ACh) release in response to α2-adrenergic stimulation as an index of in vivo cardiac vagal nerve activity. A cardiac microdialysis technique was applied to the rat left ventricle, and the effect of α2-adrenergic stimulation by intravenous medetomidine (100 μg/kg) on myocardial interstitial ACh levels was examined in anesthetized diabetic rats (4-6 weeks after intraperitoneal streptozotocin) and age-matched control rats (protocol 1). The effect of electrical vagal nerve stimulation on ACh levels was also examined in separate rats (protocol 2). In protocol 1, medetomidine increased the ACh levels in control (from 1.76 ± 0.65 to 3.13 ± 1.41 nM, P < 0.05, n = 7) but not in diabetic rats (from 2.01 ± 0.47 to 1.62 ± 0.34 nM, not significant, n = 7). In protocol 2, electrical vagal nerve stimulation at 20 Hz significantly increased the ACh levels in both control (from 1.49 ± 0.26 to 6.39 ± 1.81 nM, P < 0.001, n = 6) and diabetic rats (from 1.77 ± 0.54 to 6.98 ± 1.38 nM, P < 0.001, n = 6). In conclusion, medetomidine-induced central vagal activation was impaired in diabetic rats, whereas peripheral cardiac vagal control of ACh release was preserved. The impairment of central vagal activation may lead to relative sympathetic predominance and promote cardiovascular complications in diabetes.
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Kawada T, Shimizu S, Hayama Y, Yamamoto H, Saku K, Shishido T, Sugimachi M. Derangement of open-loop static and dynamic characteristics of the carotid sinus baroreflex in streptozotocin-induced type 1 diabetic rats. Am J Physiol Regul Integr Comp Physiol 2018; 315:R553-R567. [DOI: 10.1152/ajpregu.00092.2018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Although diabetes mellitus (DM) is a major risk factor for cardiovascular diseases, changes in open-loop static and dynamic characteristics of the arterial baroreflex in the early phase of DM remain to be clarified. We performed an open-loop systems analysis of the carotid sinus baroreflex in type 1 DM rats 4 to 5 wk after intraperitoneal streptozotocin injection ( n = 9) and we compared the results with control rats ( n = 9). The operating-point baroreflex gain was maintained in the DM rats compared with the control rats (2.07 ± 0.67 vs. 2.66 ± 0.22 mmHg/mmHg, P = 0.666). However, the range of arterial pressure (AP) control was narrower in the DM than in the control group (48.0 ± 5.0 vs. 77.1 ± 4.5 mmHg, P = 0.001), suggesting that the reserve for AP buffering is lost in DM. Although baroreflex dynamic characteristics were relatively preserved, coherences were lower in the DM than in the control group. The decreased coherence in the neural arc may be related to the narrowed quasi-linear range in the static relationship between carotid sinus pressure and sympathetic nerve activity in the DM group. Although the reason for the decreased coherences in the peripheral arc and the total reflex arc was inconclusive, the finding may indicate a loss of integrity of the baroreflex-mediated sympathetic AP control in the DM group. The derangement of the baroreflex dynamic characteristics is progressing occultly in this early stage of type 1 DM in a manner where dynamic gains are relatively preserved around the normal operating point.
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Affiliation(s)
- Toru Kawada
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Shuji Shimizu
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Yohsuke Hayama
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Hiromi Yamamoto
- Division of Cardiology, Department of Medicine, Faculty of Medicine, Kindai University, Osaka, Japan
| | - Keita Saku
- Department of Advanced Risk Stratification for Cardiovascular Diseases, Center for Disruptive Cardiovascular Medicine, Kyushu University, Fukuoka, Japan
| | - Toshiaki Shishido
- Department of Research Promotion, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Masaru Sugimachi
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
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14
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Sata Y, Head GA, Esler MD, Schlaich MP. Reply. J Hypertens 2018; 36:1606-1607. [PMID: 29847455 DOI: 10.1097/hjh.0000000000001765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Yusuke Sata
- Neurovascular Hypertension and Kidney Disease Laboratory.,Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Victoria
| | - Geoffrey A Head
- Neuropharmacology Laboratory, Baker Heart and Diabetes Institute
| | - Murray D Esler
- Neurovascular Hypertension and Kidney Disease Laboratory.,Department of Cardiovascular Medicine, Alfred Hospital
| | - Markus P Schlaich
- Neurovascular Hypertension and Kidney Disease Laboratory.,Department of Cardiovascular Medicine, Alfred Hospital.,Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Victoria.,Royal Perth Hospital Unit, Dobney Hypertension Centre, School of Medicine, University of Western Australia, Perth, Western Australia, Australia
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15
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Sata Y, Head GA, Denton K, May CN, Schlaich MP. Role of the Sympathetic Nervous System and Its Modulation in Renal Hypertension. Front Med (Lausanne) 2018; 5:82. [PMID: 29651418 PMCID: PMC5884873 DOI: 10.3389/fmed.2018.00082] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 03/15/2018] [Indexed: 12/18/2022] Open
Abstract
The kidneys are densely innervated with renal efferent and afferent nerves to communicate with the central nervous system. Innervation of major structural components of the kidneys, such as blood vessels, tubules, the pelvis, and glomeruli, forms a bidirectional neural network to relay sensory and sympathetic signals to and from the brain. Renal efferent nerves regulate renal blood flow, glomerular filtration rate, tubular reabsorption of sodium and water, as well as release of renin and prostaglandins, all of which contribute to cardiovascular and renal regulation. Renal afferent nerves complete the feedback loop via central autonomic nuclei where the signals are integrated and modulate central sympathetic outflow; thus both types of nerves form integral parts of the self-regulated renorenal reflex loop. Renal sympathetic nerve activity (RSNA) is commonly increased in pathophysiological conditions such as hypertension and chronic- and end-stage renal disease. Increased RSNA raises blood pressure and can contribute to the deterioration of renal function. Attempts have been made to eliminate or interfere with this important link between the brain and the kidneys as a neuromodulatory treatment for these conditions. Catheter-based renal sympathetic denervation has been successfully applied in patients with resistant hypertension and was associated with significant falls in blood pressure and renal protection in most studies performed. The focus of this review is the neural contribution to the control of renal and cardiovascular hemodynamics and renal function in the setting of hypertension and chronic kidney disease, as well as the specific roles of renal efferent and afferent nerves in this scenario and their utility as a therapeutic target.
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Affiliation(s)
- Yusuke Sata
- Neurovascular Hypertension and Kidney Disease Laboratory, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Faculty of Medicine, Nursing and Health Sciences, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Geoffrey A Head
- Neuropharmacology Laboratory, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Kate Denton
- Cardiovascular Program, Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Clive N May
- Preclinical Critical Care Unit, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Markus P Schlaich
- Neurovascular Hypertension and Kidney Disease Laboratory, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.,Faculty of Medicine, Nursing and Health Sciences, Central Clinical School, Monash University, Melbourne, VIC, Australia.,Dobney Hypertension Centre, School of Medicine - Royal Perth Hospital Unit, University of Western Australia, Perth, WA, Australia
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16
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Kawada T, Turner MJ, Shimizu S, Kamiya A, Shishido T, Sugimachi M. Tonic aortic depressor nerve stimulation does not impede baroreflex dynamic characteristics concomitantly mediated by the stimulated nerve. Am J Physiol Regul Integr Comp Physiol 2017; 314:R459-R467. [PMID: 29118022 DOI: 10.1152/ajpregu.00328.2017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although electrical activation of the carotid sinus baroreflex (baroreflex activation therapy) is being explored as a device therapy for resistant hypertension, possible effects on baroreflex dynamic characteristics of interaction between electrical stimulation and pressure inputs are not fully elucidated. To examine whether the electrical stimulation of the baroreceptor afferent nerve impedes normal short-term arterial pressure (AP) regulation mediated by the stimulated nerve, we electrically stimulated the right aortic depressor nerve (ADN) while estimating the baroreflex dynamic characteristics by imposing pressure inputs to the isolated baroreceptor region of the right ADN in nine anesthetized rats. A Gaussian white noise signal with a mean of 120 mmHg and standard deviation of 20 mmHg was used for the pressure perturbation. A tonic ADN stimulation (2 or 5 Hz, 10 V, 0.1-ms pulse width) decreased mean sympathetic nerve activity (367.0 ± 70.9 vs. 247.3 ± 47.2 arbitrary units, P < 0.01) and mean AP (98.4 ± 7.8 vs. 89.2 ± 4.5 mmHg, P < 0.01) during dynamic pressure perturbation. The ADN stimulation did not affect the slope of dynamic gain in the neural arc transfer function from pressure perturbation to sympathetic nerve activity (16.9 ± 1.0 vs. 14.7 ± 1.6 dB/decade, not significant). These results indicate that electrical stimulation of the baroreceptor afferent nerve does not significantly impede the dynamic characteristics of the arterial baroreflex concomitantly mediated by the stimulated nerve. Short-term AP regulation by the arterial baroreflex may be preserved during the baroreflex activation therapy.
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Affiliation(s)
- Toru Kawada
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Michael J Turner
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Shuji Shimizu
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Atsunori Kamiya
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Toshiaki Shishido
- Department of Research Promotion, National Cerebral and Cardiovascular Center , Osaka , Japan
| | - Masaru Sugimachi
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
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17
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Kawada T, Shimizu S, Yamamoto H, Miyamoto T, Kamiya A, Shishido T, Sugimachi M. Effects of different input pressure waveforms on the carotid sinus baroreflex-mediated sympathetic arterial pressure response in rats. J Appl Physiol (1985) 2017; 123:914-921. [DOI: 10.1152/japplphysiol.00354.2017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 07/05/2017] [Accepted: 07/24/2017] [Indexed: 11/22/2022] Open
Abstract
Although the pulsatility of an input pressure is an important factor that determines the arterial baroreflex responses, whether the difference in the input waveforms can meaningfully affect the baroreflex function remains unknown. This study aimed to compare baroreflex responses between two distinct pressure waveforms: a forward saw wave (FSW) and a backward saw wave (BSW). In seven anesthetized rats, carotid sinus pressure was exposed to the FSW or the BSW with a mean of 120 mmHg, pulse pressure of 40 mmHg, and pulse frequency of 1 Hz. Changes in efferent sympathetic nerve activity (SNA) and arterial pressure (AP) during six consecutive saw wave trials (FSW1, BSW1, FSW2, BSW2, FSW3, and BSW3) were examined. The steady-state SNA value during FSW1 was 91.1 ± 1.9%, which was unchanged during FSW2 and FSW3 but significantly increased during BSW1 (106.6 ± 3.4%, P < 0.01), BSW2 (110.6 ± 2.5%, P < 0.01), and BSW3 (111.6 ± 2.3%, P < 0.01). The steady-state AP value during FSW1 was 98.2 ± 8.1 mmHg, which was unchanged during FSW2 and FSW3 but significantly increased during BSW1 (106.7 ± 7.4 mmHg, P < 0.01), BSW2 (105.6 ± 7.8 mmHg, P < 0.01), and BSW3 (103.8 ± 7.2 mmHg, P < 0.05). In conclusion, the FSW was more effective than the BSW in reducing mean SNA and AP. The finding could be applied to designing an artificial pulsatile pressure such as that generated by left ventricular assist devices. NEW & NOTEWORTHY This study examined whether the waveforms of an input pressure alone can affect the baroreflex function by using a forward saw wave and a backward saw wave with the same mean pressure, pulse pressure, and pulse frequency. The forward saw wave was more effective than the backward saw wave in reducing sympathetic nerve activity and arterial pressure. The finding could be applied to designing an artificial pulsatile pressure such as that generated by left ventricular assist devices.
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Affiliation(s)
- Toru Kawada
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Shuji Shimizu
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Hiromi Yamamoto
- Faculty of Medicine, Division of Cardiology, Department of Medicine, Kindai University, Osaka, Japan
| | - Tadayoshi Miyamoto
- Graduate School of Health Sciences, Morinomiya University of Medical Sciences, Osaka, Japan; and
| | - Atsunori Kamiya
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Toshiaki Shishido
- Department of Research Promotion, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Masaru Sugimachi
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
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18
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Kawada T, Turner MJ, Shimizu S, Fukumitsu M, Kamiya A, Sugimachi M. Aortic depressor nerve stimulation does not impede the dynamic characteristics of the carotid sinus baroreflex in normotensive or spontaneously hypertensive rats. Am J Physiol Regul Integr Comp Physiol 2017; 312:R787-R796. [DOI: 10.1152/ajpregu.00530.2016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 02/06/2017] [Accepted: 02/24/2017] [Indexed: 12/29/2022]
Abstract
Recent clinical trials in patients with drug-resistant hypertension indicate that electrical activation of the carotid sinus baroreflex can reduce arterial pressure (AP) for more than a year. To examine whether the electrical stimulation from one baroreflex system impedes normal short-term AP regulation via another unstimulated baroreflex system, we electrically stimulated the left aortic depressor nerve (ADN) while estimating the dynamic characteristics of the carotid sinus baroreflex in anesthetized normotensive Wistar-Kyoto (WKY; n = 8) rats and spontaneously hypertensive rats (SHR; n = 7). Isolated carotid sinus regions were perturbed for 20 min using a Gaussian white noise signal with a mean of 120 mmHg for WKY and 160 mmHg for SHR. Tonic ADN stimulation (2 Hz, 10 V, and 0.1-ms pulse width) decreased mean sympathetic nerve activity (73.4 ± 14.0 vs. 51.6 ± 11.3 arbitrary units in WKY, P = 0.012; and 248.7 ± 33.9 vs. 181.1 ± 16.6 arbitrary units in SHR, P = 0.018) and mean AP (90.8 ± 6.6 vs. 81.2 ± 5.4 mmHg in WKY, P = 0.004; and 128.6 ± 9.8 vs. 114.7 ± 10.3 mmHg in SHR, P = 0.009). The slope of dynamic gain in the neural arc transfer function from carotid sinus pressure to sympathetic nerve activity was not different between trials with and without the ADN stimulation (12.55 ± 0.93 vs. 13.03 ± 1.28 dB/decade in WKY, P = 0.542; and 17.37 ± 1.01 vs. 17.47 ± 1.64 dB/decade in SHR, P = 0.946). These results indicate that the tonic ADN stimulation does not significantly modify the dynamic characteristics of the carotid sinus baroreflex.
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Affiliation(s)
- Toru Kawada
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Michael J. Turner
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Shuji Shimizu
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Masafumi Fukumitsu
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Atsunori Kamiya
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Masaru Sugimachi
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
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19
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Moslehpour M, Kawada T, Sunagawa K, Sugimachi M, Mukkamala R. Nonlinear identification of the total baroreflex arc: higher-order nonlinearity. Am J Physiol Regul Integr Comp Physiol 2016; 311:R994-R1003. [PMID: 27629885 DOI: 10.1152/ajpregu.00101.2016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 08/09/2016] [Accepted: 09/07/2016] [Indexed: 11/22/2022]
Abstract
The total baroreflex arc is the open-loop system relating carotid sinus pressure (CSP) to arterial pressure (AP). The nonlinear dynamics of this system were recently characterized. First, Gaussian white noise CSP stimulation was employed in open-loop conditions in normotensive and hypertensive rats with sectioned vagal and aortic depressor nerves. Nonparametric system identification was then applied to measured CSP and AP to establish a second-order nonlinear Uryson model. The aim in this study was to assess the importance of higher-order nonlinear dynamics via development and evaluation of a third-order nonlinear model of the total arc using the same experimental data. Third-order Volterra and Uryson models were developed by employing nonparametric and parametric identification methods. The R2 values between the AP predicted by the best third-order Volterra model and measured AP in response to Gaussian white noise CSP not utilized in developing the model were 0.69 ± 0.03 and 0.70 ± 0.03 for normotensive and hypertensive rats, respectively. The analogous R2 values for the best third-order Uryson model were 0.71 ± 0.03 and 0.73 ± 0.03. These R2 values were not statistically different from the corresponding values for the previously established second-order Uryson model, which were both 0.71 ± 0.03 (P > 0.1). Furthermore, none of the third-order models predicted well-known nonlinear behaviors including thresholding and saturation better than the second-order Uryson model. Additional experiments suggested that the unexplained AP variance was partly due to higher brain center activity. In conclusion, the second-order Uryson model sufficed to represent the sympathetically mediated total arc under the employed experimental conditions.
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Affiliation(s)
- Mohsen Moslehpour
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan
| | - Toru Kawada
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan; and
| | - Kenji Sunagawa
- Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Masaru Sugimachi
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan; and
| | - Ramakrishna Mukkamala
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan;
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20
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Kawada T, Akiyama T, Li M, Zheng C, Turner MJ, Shirai M, Sugimachi M. Acute arterial baroreflex-mediated changes in plasma catecholamine concentrations in a chronic rat model of myocardial infarction. Physiol Rep 2016; 4:4/15/e12880. [PMID: 27495297 PMCID: PMC4985546 DOI: 10.14814/phy2.12880] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 06/23/2016] [Indexed: 11/24/2022] Open
Abstract
While it may be predictable that plasma norepinephrine (NE) concentration changes with efferent sympathetic nerve activity (SNA) in response to baroreceptor pressure inputs, an exact relationship between SNA and plasma NE concentration remains to be quantified in heart failure. We examined acute baroreflex-mediated changes in plasma NE and epinephrine (Epi) concentrations in normal control (NC) rats and rats with myocardial infarction (MI) (n = 6 each). Plasma NE concentration correlated linearly with SNA in the NC group (slope: 2.17 ± 0.26 pg mL(-1) %(-1), intercept: 20.0 ± 18.2 pg mL(-1)) and also in the MI group (slope: 19.20 ± 6.45 pg mL(-1) %(-1), intercept: -239.6 ± 200.0 pg mL(-1)). The slope was approximately nine times higher in the MI than in the NC group (P < 0.01). Plasma Epi concentration positively correlated with SNA in the NC group (slope: 1.65 ± 0.79 pg mL(-1) %(-1), intercept: 115.0 ± 69.5 pg mL(-1)) and also in the MI group (slope: 7.74 ± 2.20 pg mL(-1) %(-1), intercept: 24.7 ± 120.1 pg mL(-1)). The slope was approximately 4.5 times higher in the MI than in the NC group (P < 0.05). Intravenous administration of desipramine (1 mg kg(-1)) significantly increased plasma NE concentration but decreased plasma Epi concentration in both groups, suggesting that neuronal NE uptake had contributed to the reduction in plasma NE concentration. These results indicate that high levels of plasma catecholamine in MI rats were still under the influence of baroreflex-mediated changes in SNA, and may provide additional rationale for applying baroreflex activation therapy in patients with chronic heart failure.
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Affiliation(s)
- Toru Kawada
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Tsuyoshi Akiyama
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Meihua Li
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Can Zheng
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Michael J Turner
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Mikiyasu Shirai
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Masaru Sugimachi
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
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21
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Abstract
Autonomic regulation therapy (ART) is a rapidly emerging therapy in the management of congestive heart failure secondary to systolic dysfunction. Modulation of the cardiac neuronal hierarchy can be achieved with bioelectronics modulation of the spinal cord, cervical vagus, baroreceptor, or renal nerve ablation. This review will discuss relevant preclinical and clinical research in ART for systolic heart failure. Understanding mechanistically what is being stimulated within the autonomic nervous system by such device-based therapy and how the system reacts to such stimuli is essential for optimizing stimulation parameters and for the future development of effective ART.
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Moslehpour M, Kawada T, Sunagawa K, Sugimachi M, Mukkamala R. Nonlinear identification of the total baroreflex arc: chronic hypertension model. Am J Physiol Regul Integr Comp Physiol 2016; 310:R819-27. [PMID: 26791831 DOI: 10.1152/ajpregu.00424.2015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 01/18/2016] [Indexed: 11/22/2022]
Abstract
The total baroreflex arc is the open-loop system relating carotid sinus pressure (CSP) to arterial pressure (AP). Its linear dynamic functioning has been shown to be preserved in spontaneously hypertensive rats (SHR). However, the system is known to exhibit nonlinear dynamic behaviors. The aim of this study was to establish nonlinear dynamic models of the total arc (and its subsystems) in hypertensive rats and to compare these models with previously published models for normotensive rats. Hypertensive rats were studied under anesthesia. The vagal and aortic depressor nerves were sectioned. The carotid sinus regions were isolated and attached to a servo-controlled piston pump. AP and sympathetic nerve activity were measured while CSP was controlled via the pump using Gaussian white noise stimulation. Second-order, nonlinear dynamics models were developed by application of nonparametric system identification to a portion of the measurements. The models of the total arc predicted AP 21-43% better (P < 0.005) than conventional linear dynamic models in response to a new portion of the CSP measurement. The linear and nonlinear terms of these validated models were compared with the corresponding terms of an analogous model for normotensive rats. The nonlinear gains for the hypertensive rats were significantly larger than those for the normotensive rats [-0.38 ± 0.04 (unitless) vs. -0.22 ± 0.03, P < 0.01], whereas the linear gains were similar. Hence, nonlinear dynamic functioning of the sympathetically mediated total arc may enhance baroreflex buffering of AP increases more in SHR than normotensive rats.
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Affiliation(s)
- Mohsen Moslehpour
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan
| | - Toru Kawada
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan; and
| | - Kenji Sunagawa
- Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Masaru Sugimachi
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan; and
| | - Ramakrishna Mukkamala
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan;
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Fukumitsu M, Kawada T, Shimizu S, Turner MJ, Uemura K, Sugimachi M. Effects of Proximal Pulmonary Artery Occlusion on Pulsatile Right Ventricular Afterload in Rats. Circ J 2016; 80:2010-8. [DOI: 10.1253/circj.cj-16-0349] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Masafumi Fukumitsu
- Department of Artificial Organ Medicine, Faculty of Medicine, Osaka University Graduate School of Medicine
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center
| | - Toru Kawada
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center
| | - Shuji Shimizu
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center
| | - Michael J. Turner
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center
| | - Kazunori Uemura
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center
| | - Masaru Sugimachi
- Department of Artificial Organ Medicine, Faculty of Medicine, Osaka University Graduate School of Medicine
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center
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24
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Kawada T, Sugimachi M. Open-loop static and dynamic characteristics of the arterial baroreflex system in rabbits and rats. J Physiol Sci 2016; 66:15-41. [PMID: 26541155 PMCID: PMC4742515 DOI: 10.1007/s12576-015-0412-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 09/30/2015] [Indexed: 02/07/2023]
Abstract
The arterial baroreflex system is the most important negative feedback system for stabilizing arterial pressure (AP). This system serves as a key link between the autonomic nervous system and the cardiovascular system, and is thus essential for understanding the pathophysiology of cardiovascular diseases and accompanying autonomic abnormalities. This article focuses on an open-loop systems analysis using a baroreceptor isolation preparation to identify the characteristics of two principal subsystems of the arterial baroreflex system, namely, the neural arc from pressure input to efferent sympathetic nerve activity (SNA) and the peripheral arc from SNA to AP. Studies on the static and dynamic characteristics of the two arcs under normal physiological conditions and also under various interventions including diseased conditions are to be reviewed. Quantitative understanding of the arterial baroreflex function under diseased conditions would help develop new treatment strategies such as electrical activation of the carotid sinus baroreflex for drug-resistant hypertension.
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Affiliation(s)
- Toru Kawada
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, 5-7-1 Fujishirodai, Suita, Osaka, 565-8565, Japan.
| | - Masaru Sugimachi
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, 5-7-1 Fujishirodai, Suita, Osaka, 565-8565, Japan
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25
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Kawada T, Sata Y, Shimizu S, Turner MJ, Fukumitsu M, Sugimachi M. Effects of tempol on baroreflex neural arc versus peripheral arc in normotensive and spontaneously hypertensive rats. Am J Physiol Regul Integr Comp Physiol 2015; 308:R957-64. [DOI: 10.1152/ajpregu.00525.2014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 03/23/2015] [Indexed: 11/22/2022]
Abstract
Although oxidative redox signaling affects arterial pressure (AP) regulation via modulation of vascular tone and sympathetic nerve activity (SNA), it remains unknown which effect plays a dominant role in the determination of AP in vivo. Open-loop systems analysis of the carotid sinus baroreflex was conducted to separately quantify characteristics of the neural arc from baroreceptor pressure input to SNA and the peripheral arc from SNA to AP in normotensive Wistar-Kyoto (WKY; n = 8) and spontaneously hypertensive rats (SHR; n = 8). Responses in SNA and AP to a staircase-wise increase in carotid sinus pressure were examined before and during intravenous administration of the membrane-permeable superoxide dismutase mimetic tempol (30 mg/kg bolus followed by 30 mg·kg−1·h−1). Two-way ANOVA indicated that tempol significantly decreased the response range of SNA (from 89.1 ± 2.4% to 60.7 ± 2.5% in WKY and from 77.5 ± 3.2% to 56.9 ± 7.3% in SHR, P < 0.001) without affecting the lower plateau of SNA (from 12.5 ± 2.4% to 9.5 ± 2.5% in WKY, and from 28.8 ± 2.8% to 30.4 ± 5.7% in SHR, P = 0.800) in the neural arc. While tempol did not affect the peripheral arc characteristics in WKY, it yielded a downward change in the regression line of AP vs. SNA in SHR. In conclusion, oxidative redox signaling plays an important role, not only in the pathological AP elevation, but also in the baroreflex-mediated physiological AP regulation. The effect of modulating oxidative redox signaling on the peripheral arc contributed to the determination of AP in SHR but not in WKY.
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Affiliation(s)
- Toru Kawada
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan; and
| | - Yusuke Sata
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan; and
- Department of Artificial Organ Medicine, Faculty of Medicine, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Shuji Shimizu
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan; and
| | - Michael J. Turner
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan; and
| | - Masafumi Fukumitsu
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan; and
- Department of Artificial Organ Medicine, Faculty of Medicine, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Masaru Sugimachi
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan; and
- Department of Artificial Organ Medicine, Faculty of Medicine, Osaka University Graduate School of Medicine, Osaka, Japan
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26
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Affiliation(s)
- Yoshitaka Hirooka
- Department of Advanced Cardiovascular Regulation and Therapeutics, Kyushu University Graduate School of Medical Sciences
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