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Fukuda Y, Kawada T, Kataoka Y, Peterson J, Saku K, Alexander J, Sunagawa K. Influence of angiotensin II and telmisartan on in vivo high-resolution renal arterial impedance in rats. Am J Physiol Regul Integr Comp Physiol 2024; 327:R349-R361. [PMID: 39005079 DOI: 10.1152/ajpregu.00009.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 06/18/2024] [Accepted: 07/03/2024] [Indexed: 07/16/2024]
Abstract
Angiotensin II (ANG II) is known to play an important role in regulating renal hemodynamics. We sought to quantify this effect in an in vivo rat model with high-resolution renal arterial (RA) impedance. This study examines the effects of ANG II and its type 1 receptor blocker telmisartan (TELM) on RA impedance. In baroreflex-deactivated rats, we measured RA pressure (Pr) and blood flow (Fr) during random ventricular pacing to induce pressure fluctuation at three different mean Pr (60, 80, and 100 mmHg). We then estimated RA impedance as the transfer function from Fr to Pr. The RA impedance was found to align with a three-element Windkessel model consisting of proximal (Rp) and distal (Rd) resistance and compliance (C). Our study showed Rd reflected the composite characteristics of afferent and efferent arterioles. Rd increased with increasing Pr under the baseline condition with a slope of 1.03 ± 0.21 (× 10-1) min·mL-1. ANG II significantly increased the slope by 0.72 ± 0.29 (× 10-1) min·mL-1 (P < 0.05) without affecting the intercept. TELM significantly reduced the intercept by 34.49 ± 4.86 (× 10-1) mmHg·min·mL-1 (P < 0.001) from the baseline value of 37.93 ± 13.36 (× 10-1) mmHg·min·mL-1, whereas it did not affect the slope. In contrast, Rp was less sensitive than Rd to ANG II or TELM, suggesting Rp may represent the characteristics of elastic large arteries. Our findings provide valuable insights into the influence of ANG II on the dynamics of the renal vasculature.NEW & NOTEWORTHY This present method of quantifying high-resolution renal arterial impedance could contribute to elucidating the characteristics of renal vasculature influenced by physiological mechanisms, renal diseases, or pharmacological effects. The present findings help construct a lumped-parameter renal hemodynamic model that reflects the influence of angiotensin II.
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Affiliation(s)
- Yukiko Fukuda
- Medical and Health Informatics Laboratories, NTT Research, Inc., Sunnyvale, California, United States
| | - Toru Kawada
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Yasuyuki Kataoka
- Medical and Health Informatics Laboratories, NTT Research, Inc., Sunnyvale, California, United States
| | - Jon Peterson
- Medical and Health Informatics Laboratories, NTT Research, Inc., Sunnyvale, California, United States
| | - Keita Saku
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
- Bio Digital Twin Center, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Joe Alexander
- Medical and Health Informatics Laboratories, NTT Research, Inc., Sunnyvale, California, United States
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Kawada T, Matsushita H, Yokota S, Yoshida Y, Fukumitsu M, Alexander J, Saku K. Short-term dynamic characteristics of diuresis during exogenous pressure perturbations with and without arterial baroreflex control. Am J Physiol Regul Integr Comp Physiol 2024; 326:R230-R241. [PMID: 38223938 DOI: 10.1152/ajpregu.00229.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 11/16/2023] [Accepted: 01/08/2024] [Indexed: 01/16/2024]
Abstract
Although body fluid volume control by the kidneys may be classified as a long-term arterial pressure (AP) control system, it does not necessarily follow that the urine flow (UF) response to changes in AP is slow. We quantified the dynamic characteristics of the UF response to short-term AP changes by changing mean AP between 60 mmHg and 100 mmHg every 10 s according to a binary white noise sequence in anesthetized rats (n = 8 animals). In a baro-on trial (the carotid sinus baroreflex was enabled), the UF response represented the combined synergistic effects of pressure diuresis (PD) and neurally mediated antidiuresis (NMA). In a baro-fix trial (the carotid sinus pressure was fixed at 100 mmHg), the UF response mainly reflected the effect of PD. The UF step response was quantified using the sum of two exponential decay functions. The fast and slow components had time constants of 6.5 ± 3.6 s and 102 ± 85 s (means ± SD), respectively, in the baro-on trial. Although the gain of the fast component did not differ between the two trials (0.49 ± 0.21 vs. 0.66 ± 0.22 µL·min-1·kg-1·mmHg-1), the gain of the slow component was greater in the baro-on than in the baro-fix trial (0.51 ± 0.14 vs. 0.09 ± 0.39 µL·min-1·kg-1·mmHg-1, P = 0.023). The magnitude of NMA relative to PD was calculated to be 32.2 ± 29.8%. In conclusion, NMA contributed to the slow component, and its magnitude was approximately one-third of that of the effect of PD.NEW & NOTEWORTHY We quantified short-term dynamic characteristics of the urine flow (UF) response to arterial pressure (AP) changes using white noise analysis. The UF step response approximated the sum of two exponential decay functions with time constants of ∼6.5 s and 102 s. The neurally mediated antidiuretic (NMA) effect contributed to the slow component of the UF step response, with the magnitude of approximately one-third of that of the pressure diuresis (PD) effect.
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Affiliation(s)
- Toru Kawada
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Hiroki Matsushita
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Shohei Yokota
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Yuki Yoshida
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Masafumi Fukumitsu
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Joe Alexander
- Medical and Health Informatics, NTT Research, Inc., Sunnyvale, California, United States
| | - Keita Saku
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
- Bio Digital Twin Center, National Cerebral and Cardiovascular Center, Osaka, Japan
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Kawada T, Miyamoto T, Fukumitsu M, Saku K. Input-size dependence of the baroreflex neural arc transfer characteristics during Gaussian white noise inputs. Am J Physiol Regul Integr Comp Physiol 2024; 326:R121-R133. [PMID: 38047314 DOI: 10.1152/ajpregu.00199.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 10/23/2023] [Accepted: 11/26/2023] [Indexed: 12/05/2023]
Abstract
Although Gaussian white noise (GWN) inputs offer a theoretical framework for identifying higher-order nonlinearity, an actual application to the data of the neural arc of the carotid sinus baroreflex did not succeed in fully predicting the well-known sigmoidal nonlinearity. In the present study, we assumed that the neural arc can be approximated by a cascade of a linear dynamic (LD) component and a nonlinear static (NS) component. We analyzed the data obtained using GWN inputs with a mean of 120 mmHg and standard deviations (SDs) of 10, 20, and 30 mmHg for 15 min each in anesthetized rats (n = 7). We first estimated the linear transfer function from carotid sinus pressure to sympathetic nerve activity (SNA) and then plotted the measured SNA against the linearly predicted SNA. The predicted and measured data pairs exhibited an inverse sigmoidal distribution when grouped into 10 bins based on the size of the linearly predicted SNA. The sigmoidal nonlinearity estimated via the LD-NS model showed a midpoint pressure (104.1 ± 4.4 mmHg for SD of 30 mmHg) lower than that estimated by a conventional stepwise input (135.8 ± 3.9 mmHg, P < 0.001). This suggests that the NS component is more likely to reflect the nonlinearity observed during pulsatile inputs that are physiological to baroreceptors. Furthermore, the LD-NS model yielded higher R2 values compared with the linear model and the previously suggested second-order Uryson model in the testing dataset.NEW & NOTEWORTHY We examined the input-size dependence of the baroreflex neural arc transfer characteristics during Gaussian white noise inputs. A linear dynamic-static nonlinear model yielded higher R2 values compared with a linear model and captured the well-known sigmoidal nonlinearity of the neural arc, indicating that the nonlinear dynamics contributed to determining sympathetic nerve activity. Ignoring such nonlinear dynamics might reduce our ability to explain underlying physiology and significantly limit the interpretation of experimental data.
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Affiliation(s)
- Toru Kawada
- 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
| | - Masafumi Fukumitsu
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Keita Saku
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
- Bio Digital Twin Center, National Cerebral and Cardiovascular Center, Osaka, Japan
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Chao-Ecija A, Dawid-Milner MS. BaroWavelet: An R-based tool for dynamic baroreflex evaluation through wavelet analysis techniques. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2023; 242:107758. [PMID: 37688995 DOI: 10.1016/j.cmpb.2023.107758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 07/28/2023] [Accepted: 08/07/2023] [Indexed: 09/11/2023]
Abstract
BACKGROUND AND OBJECTIVE Baroreflex sensitivity constitutes an indicator of the function of the baroreceptor control mechanism of blood pressure levels. It can be computed after estimating heart rate and blood pressure variability. We propose a novel tool for the evaluation of baroreflex sensitivity using wavelet analysis methods. This tool, known as BaroWavelet, incorporates an algorithm proposal based on the analysis methodology of the RHRV software package, as well as other conventional techniques. Our objectives are to develop and evaluate the tool, by testing its ability to detect changes in baroreflex sensitivity in humans. METHODS The code for this tool was designed in the R programming environment and was organized into two analysis routines and a graphical interface. Simulated recordings of blood pressure and inter-beat intervals were employed for an initial evaluation of the tool in a controlled environment. Finally, similar recordings obtained during supine and orthostatic postural evaluations, from patients that belonged to the open-access EUROBAVAR data set, were analyzed. RESULTS BaroWavelet identified the scripted changes of the baroreflex sensitivity in the simulated data. The algorithm proposal was also able to better retain additional information regarding the dynamics of the baroreflex. In the EUROBAVAR subjects, baroreflex sensitivity components were significantly smaller during orthostatism when compared with the supine position. CONCLUSIONS BaroWavelet managed to characterize baroreflex dynamics from the recordings, which were consistent with the findings reported in the literature. This demonstrates its effectiveness to perform these analyses. We suggest that this tool may be of use in research and for the evaluation of baroreflex sensitivity with clinical and therapeutic purposes. The new tool is available at the official GitHub repository of the Autonomic Nervous System Unit of the University of Málaga (https://github.com/CIMES-USNA-UMA/BaroWavelet).
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Affiliation(s)
- A Chao-Ecija
- Autonomic Nervous System Unit, CIMES, School of Medicine, University of Málaga, Spain
| | - M S Dawid-Milner
- Autonomic Nervous System Unit, CIMES, School of Medicine, University of Málaga, Spain; Instituto de Investigación Biomédica de Málaga (IBIMA), Málaga, Spain.
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Kawada T, Yokoi A, Nishiura A, Kakuuchi M, Yokota S, Matsushita H, Li M, Uemura K, Saku K. Dynamic accentuated antagonism of heart rate control during different levels of vagal nerve stimulation intensity in rats. Am J Physiol Regul Integr Comp Physiol 2023; 324:R260-R270. [PMID: 36572552 DOI: 10.1152/ajpregu.00229.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Accentuated antagonism refers to a phenomenon in which the vagal effect on heart rate (HR) is augmented by background sympathetic tone. The dynamic aspect of accentuated antagonism remains to be elucidated during different levels of vagal nerve stimulation (VNS) intensity. We performed VNS on anesthetized rats (n = 8) according to a binary white noise signal with a switching interval of 500 ms at three different stimulation rates (low-intensity: 0-10 Hz, moderate-intensity: 0-20 Hz, and high-intensity: 0-40 Hz). The transfer function from VNS to HR was estimated with and without concomitant tonic sympathetic nerve stimulation (SNS) at 5 Hz. The asymptotic low-frequency (LF) gain (in beats/min/Hz) of the transfer function increased with SNS regardless of the VNS rate [low-intensity: 3.93 ± 0.70 vs. 5.82 ± 0.65 (P = 0.021), moderate-intensity: 3.87 ± 0.62 vs. 5.36 ± 0.53 (P = 0.018), high-intensity: 4.77 ± 0.85 vs. 7.39 ± 1.36 (P = 0.011)]. Moreover, SNS slightly increased the ratio of high-frequency (HF) gain to the LF gain. These effects of SNS were canceled by the pretreatment of ivabradine, an inhibitor of hyperpolarization-activated cyclic nucleotide-gated channels, in another group of rats (n = 6). Although background sympathetic tone antagonizes the vagal effect on mean HR, it enables finer HR control by increasing the dynamic gain of the vagal HR transfer function regardless of VNS intensity. When interpreting the HF component of HR variability, the augmenting effect from background sympathetic tone needs to be considered.
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Affiliation(s)
- Toru Kawada
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Aimi Yokoi
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Akitsugu Nishiura
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Midori Kakuuchi
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Shohei Yokota
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Hiroki Matsushita
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Meihua Li
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Kazunori Uemura
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Keita Saku
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, Japan
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Yeh SJ, Lung CW, Jan YK, Liau BY. Advanced Cross-Correlation Function Application to Identify Arterial Baroreflex Sensitivity Variations From Healthy to Diabetes Mellitus. Front Neurosci 2022; 16:812302. [PMID: 35757548 PMCID: PMC9226378 DOI: 10.3389/fnins.2022.812302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 05/13/2022] [Indexed: 11/13/2022] Open
Abstract
Diabetes mellitus (DM) is a chronic disease characterized by elevated blood glucose levels, which leads over time to serious damage to the heart, blood vessels, eyes, kidneys, and nerves. DM is of two types–types 1 or 2. In type 1, there is a problem with insulin secretion, and in type 2–insulin resistance. About 463 million people worldwide have diabetes, and 80% of the majority live in low- and middle-income countries, and 1.5 million deaths are directly attributed to diabetes each year. Autonomic neuropathy (AN) is one of the common diabetic complications, leading to failure in blood pressure (BP) control and causing cardiovascular disease. Therefore, early detection of AN becomes crucial to optimize treatment. We propose an advanced cross-correlation function (ACCF) between BP and heart rate with suitable threshold parameters to analyze and detect early changes in baroreflex sensitivity (BRS) in DM with AN (DM+). We studied heart rate (HR) and systolic BP responses during tilt in 16 patients with diabetes mellitus only (DM−), 19 diabetes mellitus with autonomic dysfunction (DM+), and 10 healthy subjects. The ACCF analysis revealed that the healthy and DM groups had different filtered percentages of significant maximum cross-correlation function (CCF) value (p < 0.05), and the maximum CCF value after thresholds was significantly reduced during tilt in the DM+ group (p < 0.05). The maximum CCF index, a parameter for the phase between HR and BP, separated the healthy group from the DM groups (p < 0.05). Due to the maximum CCF index in DM groups being located in the positive range and significantly different from healthy ones, it could be speculated that BRS dysfunction in DM and AN could cause a phase change from lead to lag. ACCF could detect and separate DM+ from DM groups. This fact could represent an advantage of the ACCF algorithm. A common cross-correlation analysis was not easy to distinguish between DM− and DM+. This pilot study demonstrates that ACCF analysis with suitable threshold parameters could explore hidden changes in baroreflex control in DM+ and DM−. Furthermore, the superiority of this ACCF algorithm is useful in distinguishing whether AN is present or not in DM.
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Affiliation(s)
- Shoou-Jeng Yeh
- Section of Neurology and Neurophysiology, Cheng-Ching General Hospital, Taichung, Taiwan
| | - Chi-Wen Lung
- Department of Creative Product Design, Asia University, Taichung, Taiwan.,Rehabilitation Engineering Laboratory, Kinesiology and Community Health, Computational Science and Engineering, University of Illinois at Urbana-Champaign, Champaign, IL, United States
| | - Yih-Kuen Jan
- Rehabilitation Engineering Laboratory, Kinesiology and Community Health, Computational Science and Engineering, University of Illinois at Urbana-Champaign, Champaign, IL, United States
| | - Ben-Yi Liau
- Department of Biomedical Engineering, Hungkuang University, Taichung, Taiwan
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