Input-size dependence of the baroreflex neural arc transfer characteristics

Kawada, Toru; Yanagiya, Yusuke; Uemura, Kazunori; Miyamoto, Tadayoshi; Zheng, Can; Li, Meihua; Sugimachi, Masaru; Sunagawa, Kenji

doi:10.1152/ajpheart.00319.2002

Cited by 33 publications

(46 citation statements)

References 22 publications

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“…When CSP was perturbed around the operating-point pressure, however, mean SNA and AP usually decreased (10). The phenomenon may be related to the input pulsatility and the effect of input amplitude (3,17,35). Mean SNA and AP are expected to decrease as the input amplitude of CSP perturbation increases when the mean CSP is lower than the midpoint of the inverse sigmoidal curve characterizing the CSP-SNA relationship.…”

Section: Discussionmentioning

confidence: 99%

Dynamic characteristics of baroreflex neural and peripheral arcs are preserved in spontaneously hypertensive rats

Kawada

Shimizu

Kamiya

et al. 2011

American Journal of Physiology-Regulatory, Integrative and Comp

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Although baroreceptors are known to reset to operate in a higher pressure range in spontaneously hypertensive rats (SHR), the total profile of dynamic arterial pressure (AP) regulation remains to be clarified. We estimated open-loop transfer functions of the carotid sinus baroreflex in SHR and Wistar Kyoto (WKY) rats. Mean input pressures were set at 120 (WKY120 and SHR120) and 160 mmHg (SHR160). The neural arc transfer function from carotid sinus pressure to efferent splanchnic sympathetic nerve activity (SNA) revealed derivative characteristics in both WKY and SHR. The slope of dynamic gain (in decibels per decade) between 0.1 and 1 Hz was not different between WKY120 (10.1 ± 1.0) and SHR120 (10.4 ± 1.1) but was significantly greater in SHR160 (13.2 ± 0.8, P < 0.05 with Bonferroni correction) than in SHR120. The peripheral arc transfer function from SNA to AP showed low-pass characteristics. The slope of dynamic gain (in decibels per decade) did not differ between WKY120 (−34.0 ± 1.2) and SHR120 (−31.4 ± 1.0) or between SHR120 and SHR160 (−32.8 ± 1.3). The total baroreflex showed low-pass characteristics and the dynamic gain at 0.01 Hz did not differ between WKY120 (0.91 ± 0.08) and SHR120 (0.84 ± 0.13) or between SHR120 and SHR160 (0.83 ± 0.11). In both WKY and SHR, the declining slope of dynamic gain was significantly gentler for the total baroreflex than for the peripheral arc, suggesting improved dynamic AP response in the total baroreflex. In conclusion, the dynamic characteristics of AP regulation by the carotid sinus baroreflex were well preserved in SHR despite significantly higher mean AP.

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Section: Discussionmentioning

confidence: 99%

Dynamic characteristics of baroreflex neural and peripheral arcs are preserved in spontaneously hypertensive rats

Kawada

Shimizu

Kamiya

et al. 2011

American Journal of Physiology-Regulatory, Integrative and Comp

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“…2). The phenomenon may be explained by the difference in the input amplitude [32]. Mean SNA and AP decrease as the input amplitude of CSP perturbation increases when mean CSP is lower than the midpoint pressure (P MID ) of the static CSP-SNA relationship [33].…”

Section: Discussionmentioning

confidence: 99%

Intravenous Angiotensin II Does Not Affect Dynamic Baroreflex Characteristics of the Neural or Peripheral Arc

Kashihara

Takahashi²,

Chatani³

et al. 2003

JJP

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The arterial baroreflex system is one of the most important negative-feedback systems that stabilizes arterial pressure (AP) against exogenous pressure perturbation. The arterial baroreflex may be divided into the neural and peripheral arc subsystems [1][2][3]. The neural arc represents the signal transduction pathway from baroreceptor pressure input to efferent sympathetic nerve activity (SNA). The peripheral arc represents the regulatory pathway from SNA to AP. Static characteristics of the two arcs provide information on the operating point of AP regulation [2,4]. The dynamic characteristics of the two arcs determine the stability and quickness of AP regulation [1,5]. Because the baroreflex operates dynamically under the ordinary conditions of daily activity, changes in baroreflex dynamic characteristics critically affect the performance of AP regulation and consequently have an impact on quality of life. An assessment of baroreflex dynamic characteristics in conjunction with altered hormonal regulation of the cardiovascular sys- Key words: renal sympathetic nerve activity, transfer function, systems analysis, rabbits, carotid sinus baroreflex.Abstract: Although the elevation of angiotensin II (Ang II) associated with cardiovascular diseases has been considered to suppress the arterial baroreflex function, how Ang II affects dynamic arterial pressure (AP) regulation remains unknown. The aim of the present study was to elucidate the acute effects of Ang II on dynamic AP regulation by the arterial baroreflex. In seven anesthetized Japanese white rabbits, we randomly perturbed intra-carotid sinus pressure (CSP) according to a binary white noise sequence while recording renal sympathetic nerve activity (RSNA) and AP. We estimated the neural arc transfer function from CSP to RSNA and the peripheral arc transfer function from RSNA to AP before and after 30-min intravenous administration of Ang II (100 ng/kg/min). Ang II increased mean

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“…5 and Table 3). Also, in a previous study (13), changes in input power did not significantly affect the peripheral arc transfer function. Judging from the static input-output characteristics, the SNA-AP relationship is much more linear than the CSP-SNA relationship (25).…”

Section: Effects Of Pbg On Neural and Peripheral Arc Transfer Charactmentioning

confidence: 48%

“…Furthermore, the effects of the BJ reflex on the arterial baroreflex have not been assessed separately with regard to the neural and peripheral arc transfer characteristics. Therefore, to test the hypothesis that the BJ reflex modulates the dynamic characteristics of the total loop, neural arc, and/or peripheral arc of the arterial baroreflex, we performed a baroreflex open-loop experiment by using a white noise method in anesthetized rabbits (6,13,26). The results of the present study indicate that the BJ reflex evoked by intravenous PBG administration reduced dynamic gain in the total baroreflex loop, mainly by attenuating dynamic gain in the neural arc.…”

mentioning

confidence: 70%

Bezold-Jarisch reflex attenuates dynamic gain of baroreflex neural arc

Kashihara

Kawada²,

Yanagiya³

et al. 2003

American Journal of Physiology-Heart and Circulatory Physiology

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risch reflex attenuates dynamic gain of baroreflex neural arc. Am J Physiol Heart Circ Physiol 285: H833-H840, 2003. First published April 24, 2003 10.1152/ajpheart.01082. 2002-Although acute myocardial ischemia or infarction may induce the Bezold-Jarisch (BJ) reflex through the activation of serotonin receptors on vagal afferent nerves, the mechanism by which the BJ reflex modulates the dynamic characteristics of arterial pressure (AP) regulation is unknown. The purpose of this study was to examine the effects of the BJ reflex induced by intravenous phenylbiguanide (PBG) on the dynamic characteristics of the arterial baroreflex. In seven anesthetized rabbits, we perturbed intracarotid sinus pressure (CSP) according to a white noise sequence while renal sympathetic nerve activity (RSNA), AP, and heart rate (HR) were recorded. We estimated the transfer function from CSP to RSNA (neural arc) and from RSNA to AP (peripheral arc) before and after 10 min of intravenous administration of PBG (100 g ⅐ kg Ϫ1 ⅐ min Ϫ1 ). The intravenous PBG decreased mean AP from 84.5 Ϯ 4.0 to 68.2 Ϯ 4.7 mmHg (P Ͻ 0.01), mean RSNA to 76.2 Ϯ 7.0% (P Ͻ 0.05), and mean HR from 301.6 Ϯ 7.7 to 288.4 Ϯ 9.0 beats/min (P Ͻ 0.01). The intravenous PBG significantly decreased neural arc dynamic gain at 0.01 Hz (1.06 Ϯ 0.08 vs. 0.59 Ϯ 0.17, P Ͻ 0.05), whereas it did not affect that of the peripheral arc (1.20 Ϯ 0.12 vs. 1.18 Ϯ 0.41). In six different rabbits without intravenous PBG, the neural arc transfer function did not change between two experimental runs with intervening interval of 10 min, excluding the possibility that the cumulative effects of anesthetics had altered the neural arc transfer function. In conclusion, excessive activation of the BJ reflex during acute myocardial ischemia may exert an adverse effect on AP regulation, not only by sympathetic suppression, but also by attenuating baroreflex dynamic gain. renal sympathetic nerve activity; transfer function; systems analysis; rabbits; carotid sinus baroreflex THE CIRCULATORY SYSTEM has several mechanoreceptors and chemoreceptors in a variety of regions. The cardiopulmonary region is rich in such receptors. The most vagal afferent fibers from the cardiopulmonary receptors to the vasomotor center are classified as C fibers.Activation of the cardiopulmonary chemosensitive vagal afferent fibers reduces arterial pressure (AP), heart rate (HR), and cardiac output (31). These responses, mediated by 5-hydroxytryptamine (5-HT 3 ) serotonergic receptors on the cardiopulmonary vagal afferent fibers, are known as the Bezold-Jarisch (BJ) reflex (2, 7, 32). Although its physiological importance remains debatable, the BJ reflex could play a significant role in developing pathological responses associated with acute myocardial ischemia (19,20,24). Elucidating the effects of the BJ reflex on the circulatory regulation would be useful for better understanding the pathophysiology of ischemic heart diseases (16, 27). The BJ reflex can be induced chemically with pharmacological agents such as 5-HT and ...

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Input-size dependence of the baroreflex neural arc transfer characteristics

Cited by 33 publications

References 22 publications

Dynamic characteristics of baroreflex neural and peripheral arcs are preserved in spontaneously hypertensive rats

Dynamic characteristics of baroreflex neural and peripheral arcs are preserved in spontaneously hypertensive rats

Intravenous Angiotensin II Does Not Affect Dynamic Baroreflex Characteristics of the Neural or Peripheral Arc

Bezold-Jarisch reflex attenuates dynamic gain of baroreflex neural arc

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