Interaction between vestibulo-cardiovascular reflex and arterial baroreflex during postural change in rats

2011 ◽  
Vol 111 (6) ◽  
pp. 1614-1621 ◽  
Author(s):  
Chikara Abe ◽  
Toru Kawada ◽  
Masaru Sugimachi ◽  
Hironobu Morita
Keyword(s):  
Vestibular System ◽  
Carotid Sinus ◽  
Open Loop ◽  
Operating Point ◽  
Arterial Baroreflex ◽  
Postural Change ◽  
Cardiovascular Reflex ◽  
Head Up Tilt ◽  
Freely Moving ◽  
Sinus Pressure

To examine a cooperative role for the baroreflex and the vestibular system in controlling arterial pressure (AP) during voluntary postural change, AP was measured in freely moving conscious rats, with or without sinoaortic baroreceptor denervation (SAD) and/or peripheral vestibular lesion (VL). Voluntary rear-up induced a slight decrease in AP (−5.6 ± 0.8 mmHg), which was significantly augmented by SAD (−14.7 ± 1.0 mmHg) and further augmented by a combination of VL and SAD (−21 ± 1.0 mmHg). Thus we hypothesized that the vestibular system sensitizes the baroreflex during postural change. To test this hypothesis, open-loop baroreflex analysis was conducted on anesthetized sham-treated and VL rats. The isolated carotid sinus pressure was increased stepwise from 60 to 180 mmHg while rats were placed horizontal prone or in a 60° head-up tilt (HUT) position. HUT shifted the carotid sinus pressure-sympathetic nerve activity (SNA) relationship (neural arc) to a higher SNA, shifted the SNA-AP relationship (peripheral arc) to a lower AP, and, consequently, moved the operating point to a higher SNA while maintaining AP (from 113 ± 5 to 114 ± 5 mmHg). The HUT-induced neural arc shift was completely abolished in VL rats, whereas the peripheral arc shifted to a lower AP and the operating point moved to a lower AP (from 116 ± 3 to 84 ± 5 mmHg). These results indicate that the vestibular system elicits sympathoexcitation, shifting the baroreflex neural arc to a higher SNA and maintaining AP during HUT.

scholarly journals Acute Effects of Vagotomy on Baroreflex Equilibrium Diagram in Rats with Chronic Heart Failure

2016 ◽  
Vol 10 ◽  
pp. CMC.S38443 ◽  
Author(s):  
Toru Kawada ◽  
Meihua Li ◽  
Can Zheng ◽  
Masaru Sugimachi
Keyword(s):  
Heart Failure ◽  
Carotid Sinus ◽  
Equilibrium Diagram ◽  
Open Loop ◽  
Operating Point ◽  
Arterial Baroreflex ◽  
Static Characteristics ◽  
Acute Effects ◽  
Vagal Modulation ◽  
Carotid Sinus Baroreflex

The arterial baroreflex system can be divided into the neural arc, from pressure input to efferent sympathetic nerve activity (SNA), and the peripheral arc, from SNA to arterial pressure (AP). Plotting the neural and peripheral arcs on a pressure–SNA plane yields a baroreflex equilibrium diagram. We examined the effects of vagotomy on the open-loop static characteristics of the carotid sinus baroreflex in normal control rats (NC, n = 10) and rats with heart failure after myocardial infarction (MI, n = 10). In the NC group, vagotomy shifted the neural arc toward higher SNA and decreased the slope of the peripheral arc. Consequently, the operating-point SNA increased without a significant change in the operating-point AP on the baroreflex equilibrium diagram. These vagotomy-induced effects were not observed in the MI group, suggesting a loss of vagal modulation of the carotid sinus baroreflex function in heart failure.

Carotid sinus control of pulsatile hemodynamics in halothane-anesthetized dogs

1980 ◽  
Vol 238 (3) ◽  
pp. H294-H299
Author(s):  
R. H. Cox ◽  
R. J. Bagshaw
Keyword(s):  
Arterial Pressure ◽  
Carotid Sinus ◽  
Open Loop ◽  
Hydraulic Power ◽  
Set Point ◽  
Hemodynamic Variables ◽  
Vascular Impedance ◽  
Mean Pressure ◽  
Anesthetized Dogs ◽  
Sinus Pressure

The open-loop characteristics of the carotid sinus baroreceptor reflex control of pulsatile arterial pressure-flow relations were studied in halothane-anesthetized dogs. Pressures and flows were measured in the ascending aorta, the celiac, mesenteric, renal, and iliac arteries and were used to compute values of regional vascular impedance and hydraulic power. The carotid sinuses were bilaterally isolated and perfused under conditions of controlled mean pressure with a constant sinusoidal component. Measurements were made with the vagi intact and after bilateral vagotomy. Maximum values of open-loop gain averaged -0.78 +/- 0.08 before and -1.42 +/- 0.20 after vagotomy. Vagotomy produced significant increases in the variation of all hemodynamic variables with carotid sinus pressure that were nonuniformly affected in the various regional vascular beds. Aortic and regional vascular impedance showed significant variations with carotid sinus pressure that were augmented by vagotomy. Aortic impedance exhibited a minimum at the normal set point. These results indicate that a) carotid sinus baroreflexes are well preserved with halothane anesthesia, b) thoracic baroreceptor-mediated reflexes exert significant hemodynamic effects on systemic hemodynamics around normal set point values of arterial pressure, c) systemic baroreceptors exert control over large as well as small vessel properties, and d) the baroreceptor-mediated reflexes produce significant influences on hydraulic power and its components.

scholarly journals Derangement of open-loop static and dynamic characteristics of the carotid sinus baroreflex in streptozotocin-induced type 1 diabetic rats

2018 ◽  
Vol 315 (3) ◽  
pp. R553-R567 ◽  
Author(s):  
Toru Kawada ◽  
Shuji Shimizu ◽  
Yohsuke Hayama ◽  
Hiromi Yamamoto ◽  
Keita Saku ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Carotid Sinus ◽  
Early Stage ◽  
Open Loop ◽  
Operating Point ◽  
Control Group ◽  
Static And Dynamic Characteristics ◽  
Carotid Sinus Baroreflex ◽  
Type 1 Dm

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.

Rabbit carotid sinus reflex under pentobarbital, urethan, and chloralose anesthesia

1984 ◽  
Vol 246 (5) ◽  
pp. H696-H701 ◽  
Author(s):  
N. Ishikawa ◽  
C. H. Kallman ◽  
K. Sagawa
Keyword(s):  
Heart Rate ◽  
Arterial Pressure ◽  
Carotid Sinus ◽  
Logistic Function ◽  
Systemic Arterial Pressure ◽  
Open Loop ◽  
Specific Effects ◽  
Reflex Control ◽  
Alpha Chloralose ◽  
Sinus Pressure

To determine the effects of different anesthesias on the performance of the arterial baro-reflex, the open-loop characteristic of the carotid sinus reflex was analyzed in 24 rabbits under anesthesia with pentobarbital (30 mg/kg), urethan (800 mg/kg), alpha-chloralose (80 mg/kg), or a mixture of alpha-chloralose (40 mg/kg) and urethan (0.4 g/kg). For each rabbit and anesthesia, mean systemic arterial pressure and heart rate were measured as carotid sinus pressure was changed in 10-mmHg steps between 40 and 150 mmHg. This set of measurements was repeated four times at 1-h intervals. A logistic function curve was fitted to the carotid sinus pressure-arterial pressure relationship. The parameters of this curve were then analyzed to delineate the specific effects of the anesthesias on the relationship. The main finding was that the response range and the slope parameters under alpha-chloralose anesthesia were significantly smaller than those obtained under the other anesthesias. Propylene glycol, used as the solvent for chloralose, did not affect the reflex control of arterial pressure or heart rate. The reflex under chloralose-urethan anesthesia showed characteristics similar to those under urethan anesthesia. We conclude that although alpha-chloralose has traditionally been used in the dog to obtain strong reflex responses, it weakens the reflex control of arterial pressure in the rabbit.

scholarly journals Contrasting open-loop dynamic characteristics of sympathetic and vagal systems during baroreflex-mediated heart rate control in rats

2019 ◽  
Vol 317 (6) ◽  
pp. R879-R890 ◽  
Author(s):  
Toru Kawada ◽  
Hiromi Yamamoto ◽  
Yohsuke Hayama ◽  
Takuya Nishikawa ◽  
Kunihiko Tanaka ◽  
...  
Keyword(s):  
Heart Rate ◽  
Transfer Function ◽  
Dynamic Characteristics ◽  
Carotid Sinus ◽  
Gaussian White Noise ◽  
Open Loop ◽  
Model Parameters ◽  
Before And After ◽  
Dynamic Gain ◽  
Sinus Pressure

Although heart rate (HR) is governed by the sympathetic and parasympathetic nervous systems, a head-to-head comparison of the open-loop dynamic characteristics of the total arc from a baroreceptor pressure input to the HR response has yet to be performed. We estimated the transfer function from carotid sinus pressure input to the HR response ( HCSP→HR) before and after bilateral vagotomy ( n = 7) as well as before and after the administration of a β-blocker propranolol ( n = 8) in anesthetized male Wistar-Kyoto rats. The carotid sinus pressure was perturbed according to a Gaussian white noise signal so that the input power spectra were relatively flat between 0.01 and 1 Hz. The gain plot of HCSP→HR was V-shaped. Vagotomy reduced the dynamic gain at 1 Hz (0.0598 ± 0.0065 to 0.0025 ± 0.0004 beats·min−1·mmHg−1, P < 0.001) but not at 0.01 or 0.1 Hz. β-Blockade reduced the dynamic gain at 0.01 Hz (0.247 ± 0.069 to 0.077 ± 0.017 beats·min−1·mmHg−1, P = 0.020) but not at 0.1 or 1 Hz. We also estimated the efferent limb transfer function from electrical vagal efferent stimulation to the HR response ( HVN→HR) under β-blockade conditions. We associated the model parameters of HVN→HR with the mean HR and the standard deviation of HR so that HVN→HR could be estimated based only on the HR data. We finally estimated the neural arc transfer function from a pressure input to efferent vagal nerve activity by dividing HCSP→HR by HVN→HR. The mathematically determined vagal neural arc showed derivative characteristics with its phase near zero radians at the lowest frequency.

Baroreceptor influence on a spinal cardiovascular reflex

1979 ◽  
Vol 57 (2) ◽  
pp. 147-151
Author(s):  
Franco Lioy ◽  
Peter M. Szeto
Keyword(s):  
Arterial Pressure ◽  
Thoracic Aorta ◽  
Carotid Sinus ◽  
Reflex Response ◽  
Carotid Sinus Nerve ◽  
Arterial Blood ◽  
Cardiovascular Reflex ◽  
Baroreceptor Stimulation ◽  
Spinal Section ◽  
Sinus Pressure

A stretch of the walls of the thoracic aorta, performed in vagotomized cats without obstructing aortic flow, induces increases in heart rate, myocardial contractility, and arterial pressure. These reflex responses are still present after high spinal section. Cats under chloralose–urethane anesthesia were vagotomized and one carotid sinus was isolated and perfused with arterial blood at constant flow. The contralateral carotid sinus nerve and both aortic nerves were sectioned. A stretch of the walls of the thoracic aorta between the 7th and 10th intercostal arteries induced a reflex increase in mean arterial pressure of 29 ± 2 mmHg (mean ± SE). Stepwise increases of carotid sinus pressure (CSP) or electrical stimulation of the carotid sinus nerve induced stepwise decreases of this reflex response. At maximal baroreceptor stimulation (CSP 212 ± 9 mmHg) the reflex response to aortic stretch was reduced by 42%.These experiments show that this spinal cardiovascular reflex is at least partially under the inhibitory control of the baroreceptor input.

Carotid baroreflex responsiveness during dynamic exercise in humans

1993 ◽  
Vol 265 (6) ◽  
pp. H1928-H1938 ◽  
Author(s):  
J. T. Potts ◽  
X. R. Shi ◽  
P. B. Raven
Keyword(s):  
Carotid Sinus ◽  
Systemic Blood Pressure ◽  
Logistic Function ◽  
Peak Oxygen Uptake ◽  
Open Loop ◽  
Operating Point ◽  
Baroreflex Control ◽  
Carotid Baroreflex ◽  
Maximal Sensitivity ◽  
Neck Pressure

We utilized 5-s changes of neck pressure and neck suction (from 40 to -80 Torr) to alter carotid sinus transmural pressure in seven men with peak oxygen uptake (VO2peak) of 41.4 +/- 3.6 ml O2.kg-1.min-1. Peak responses of heart rate (HR) and mean arterial pressure (MAP) to each carotid sinus perturbation were used to construct open-loop baroreflex curves at rest and during exercise at 25.7 +/- 1.1 and 47.4 +/- 1.9% VO2peak. The baroreflex curves were fit to a logistic function describing the sigmoidal nature of the carotid sinus baroreceptor reflex. Maximal gain for baroreflex control of HR (-0.31 +/- 0.05 beats.min-1.mmHg-1) and MAP (-0.30 +/- 0.08 mmHg/mmHg) at rest was the same as during exercise at 25 and 50% VO2peak (-0.30 +/- 0.05, -0.39 +/- 0.13 beats.min-1.mmHg-1 for HR, P = NS; -0.23 +/- 0.04, -0.60 +/- 0.38 mmHg/mmHg for MAP, P = NS). Resetting of the baroreflex occurred during exercise at 50% VO2peak. The centering point, threshold, and saturation pressures were significantly increased for baroreflex control of HR (delta pressure = 26.3 +/- 6.8, 19.6 +/- 10.4, 33.0 +/- 5.6 mmHg, P < 0.05) and MAP (delta pressure = 27.1 +/- 7.7, 16.1 +/- 14.8, 38.2 +/- 8.5 mmHg, P < 0.05). The operating point (steady-state HR and MAP) was shifted closer to threshold of the baroreflex during exercise at 50% VO2peak, as reflected by differences in HR and MAP between the centering and operating points (delta HR = 12.5 +/- 4.7 beats/min, P = 0.10; delta MAP = 7.6 +/- 1.3 mmHg, P < 0.05). These findings suggest a resetting of the carotid baroreflex during exercise with no attenuation in maximal sensitivity. A shift in operating point toward threshold of the baroreflex enables effective buffering of elevations in systemic blood pressure via reflex alterations in HR and MAP.

Effects of pulsations on carotid sinus control of regional arterial hemodynamics

1980 ◽  
Vol 238 (2) ◽  
pp. H182-H190 ◽  
Author(s):  
R. H. Cox ◽  
R. J. Bagshaw
Keyword(s):  
Carotid Sinus ◽  
Peripheral Resistance ◽  
Aortic Pressure ◽  
Operating Point ◽  
Systemic Hemodynamic ◽  
Arterial Hemodynamics ◽  
Hemodynamic Variables ◽  
Anesthetized Dogs ◽  
Mean Aortic Pressure ◽  
Sinus Pressure

Studies were conducted in halothane-anesthetized dogs to evaluate the interaction of mean and pulsatile components of carotid sinus perfusion pressure on the control of regional pressure-flow relations. Pressure and flow were measured simultaneously in the ascending aorta, celiac, mesenteric, renal, and iliac arteries. The carotid sinuses were bilaterally isolated and perfused under controlled conditions. Mean (CSP) and pulsatile components (CSPP) of carotid sinus pressure were varied systemically. Values of mean aortic pressure (AP) at the operating point (AP = CSP) decreased with increasing CSPP (127 +/- 5 at CSPP = 0 to 103 +/- 5 at CSPP = 60). Reflex gains at the operating point also decreased with increasing CSPP (-1.35 +/- 0.16 for CSPP = 0 to -0.92 +/- 0.18 for CSPP = 60). Changes in cardiac output and peripheral resistance nonuniformly contributed to these responses, with the former predominating at low CSPP and the later at high CSPP. Operating-point values of regional resistance generally decreased with increasing CSPP but to different degrees in the various beds. With increasing CSPP amplitude, regional resistance sensitivity at the operating point (i.e., slope) increased in the celiac and decreased in the mesenteric, renal, and iliac vascular beds. Separate changes in mean and pulsatile components of carotid sinus pressure about the normal operating point produce quantitatively similar changes in systemic hemodynamic variables.

Baroreceptor reflex cardiovascular control in mongrel dogs and racing greyhounds

1985 ◽  
Vol 249 (3) ◽  
pp. H655-H662 ◽  
Author(s):  
R. H. Cox ◽  
R. J. Bagshaw ◽  
D. K. Detweiler
Keyword(s):  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Carotid Sinus ◽  
Open Loop ◽  
Baroreceptor Reflex ◽  
Operating Point ◽  
Baroreflex Control ◽  
Pulsatile Pressure ◽  
Carotid Sinus Baroreflex ◽  
Before And After

The open-loop carotid sinus baroreflex control of arterial pressure-flow relations were compared in mongrel dogs and racing greyhounds (GH) anesthetized with alpha-chloralose. The carotid sinuses were bilaterally isolated and perfused under controlled pressure. Pulsatile pressure and flow were simultaneously measured in the ascending aorta, the celiac, superior mesenteric, left renal, and right iliac arteries. Open-loop set point values of mean arterial pressure were higher in GH before and after vagotomy. Reflex gains were similar before vagotomy but lower in GH after vagotomy. The overall range of control of arterial pressure was the same before vagotomy but smaller in GH after vagotomy. The variation of mean arterial pressure with mean carotid sinus pressure in GH was shifted toward higher pressure levels similar to resetting. The overall effects of vagotomy on carotid sinus baroreceptor reflex responses were smaller in GH. Operating point values of regional resistance were generally smaller in GH. Operating point sensitivities of regional resistance were the same except for the iliac bed, which was more sensitive in GH. These results document significant regional differences in the baroreceptor control of regional hemodynamics between mongrels and greyhounds that could contribute to altered responses especially to "hypertensive" perturbations.

Exercise training and the arterial baroreflex

1987 ◽  
Vol 63 (5) ◽  
pp. 1926-1932 ◽  
Author(s):  
T. G. Bedford ◽  
C. M. Tipton
Keyword(s):  
Blood Pressure ◽  
Exercise Training ◽  
Endurance Training ◽  
Carotid Sinus ◽  
Maximal Response ◽  
Peripheral Blood Flow ◽  
Arterial Baroreflex ◽  
Baroreflex Control ◽  
Carotid Sinus Baroreflex ◽  
Sinus Pressure

To test the hypothesis that endurance training would attenuate the carotid sinus baroreflex in rats, studies were undertaken with 25 nontrained (NT) and 22 trained (T) male Sprague-Dawley rats that were exercised for 11–14 wk. Maximal O2 consumption was significantly increased 10% after training. The left carotid sinus region was functionally isolated in anesthetized animals. Subsequently, static carotid sinus pressure was raised in 20-Torr increments from 95 Torr until a maximal response in systemic arterial pressure and regional blood flows was recorded. Compared with the NT group, baroreflex control of blood pressure and calculated regional resistance of the T animals was less responsive to changes in carotid sinus pressure. Resting blood pressure, heart rate, and changes in peripheral blood flow velocity were similar for the two groups. Peripheral sensitivity to phenylephrine-HCl and hexamethonium bromide were also similar in the T and NT groups. It was concluded that the arterial baroreflex control of blood pressure was attenuated by exercise training. These findings support the concept that the trained individual is at disadvantage during hypotensive episodes and that endurance training will attenuate the sympathetic component of the arterial baroreflex.

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