scholarly journals Open‐loop static characteristics of the carotid sinus baroreflex in rats fed a high‐fat diet

2013 ◽  
Vol 27 (S1) ◽  
Author(s):  
Chikara Abe ◽  
Chihiro Iwata ◽  
Hironobu Morita
Keyword(s):  
High Fat Diet ◽  
Carotid Sinus ◽  
Open Loop ◽  
Static Characteristics ◽  
High Fat ◽  
Carotid Sinus Baroreflex

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.

Closed-loop identification of carotid sinus baroreflex open-loop transfer characteristics in rabbits

1997 ◽  
Vol 273 (2) ◽  
pp. H1024-H1031 ◽  
Author(s):  
T. Kawada ◽  
M. Sugimachi ◽  
T. Sato ◽  
H. Miyano ◽  
T. Shishido ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Closed Loop ◽  
Transfer Functions ◽  
Carotid Sinus ◽  
Open Loop ◽  
Parametric Models ◽  
Efferent Nerve ◽  
Transfer Characteristics ◽  
Carotid Sinus Baroreflex ◽  
Closed Loop Identification

In the circulatory system, a change in blood pressure operates through the baroreflex to alter sympathetic efferent nerve activity, which in turn affects blood pressure. Existence of this closed feedback loop makes it difficult to identify the baroreflex open-loop transfer characteristics by means of conventional frequency domain approaches. Although several investigators have demonstrated the advantages of the time domain approach using parametric models such as the autoregressive moving average model, specification of the model structure critically affects their results. Thus we investigated the applicability of a nonparametric closed-loop identification technique to the carotid sinus baroreflex system by using an exogenous perturbation according to a binary white-noise sequence. To validate the identification method, we compared the transfer functions estimated by the closed-loop identification with those estimated by open-loop identification. The transfer functions determined by the two identification methods did not differ statistically in their fitted parameters. We conclude that exogenous perturbation to the baroreflex system enables us to estimate the open-loop baroreflex transfer characteristics under closed-loop conditions.

Lack of time-dependent augmentation of carotid sinus baroreflex system after vagotomy

1982 ◽  
Vol 242 (4) ◽  
pp. H580-H584
Author(s):  
H. Hosomi ◽  
K. Yokoyama
Keyword(s):  
Control System ◽  
Arterial Pressure ◽  
Carotid Sinus ◽  
Pressure Control ◽  
Open Loop ◽  
Carotid Sinus Baroreflex ◽  
Stepwise Reduction ◽  
Intact Condition ◽  
Pressure Control System ◽  
Arterial Pressure Control System

The purpose of this experiment was to study whether the carotid sinus baroreflex system (CS system) increases its gain with time after vagotomy in compensation for the loss of the vagally mediated arterial pressure control system (V system). In 7 dogs anesthetized with pentobarbital sodium we determined the responsiveness of the V system by repeatedly measuring the overall open-loop gain (G) of the negative feedback control system. G was assessed as (delta API/delta APS) -- 1, where delta API and delta APS are, respectively, the immediate and steady-state falls in arterial pressure at the aortic arch following a stepwise reduction in blood volume. delta API, delta APS, and G in intact condition were -12.0 +/- 1.8 mmHg, -1.1 +/- 0.2 mmHg, and 10.1 +/- 0.7 (SD), respectively. delta API, delta APS, and G after vagotomy, i.e., G of the CS system (GCS), were -15.6 +/- 3.6 mmHg, -6.4 +/- 1.9 mmHg, and 1.6 +/- 0.4 GCS did not change with time over 4 h after vagotomy. We conclude that the CS system cannot augment its ability to restore arterial pressure in compensation for the lost function of the V system within 4 h after vagotomy in the anesthetized dog.

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.

Role of carotid sinus baroreflex in attenuating systemic arterial pressure variability studied in anesthetized dogs

1994 ◽  
Vol 266 (2) ◽  
pp. H720-H729 ◽  
Author(s):  
T. Yoshida ◽  
Y. Harasawa ◽  
T. Kubota ◽  
H. Chishaki ◽  
T. Kubo ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Carotid Sinus ◽  
Amplitude Spectrum ◽  
Low Frequency ◽  
Systemic Arterial Pressure ◽  
Open Loop ◽  
Frequency Range ◽  
Carotid Sinus Baroreflex ◽  
Anesthetized Dogs

Attenuation of systemic arterial pressure (SAP) variability by the carotid sinus baroreflex (CSBR) was quantified in nine anesthetized, vagotomized dogs. SAP amplitude spectrum was compared between open-loop [SAPo(f)] and closed-loop [SAPc(f)] operation of the CSBR. At 0.002 Hz, SAPc amplitude was 3.5 +/- 2.2 (SD) mmHg, and SAPo was 9.6 +/- 3.5 mmHg (P < 0.01). At 0.02 Hz, SAP(c) amplitude was 2.8 +/- 1.2 mmHg, and SAPo was 4.3 +/- 1.2 mmHg (P < 0.05). At higher frequencies, SAPo(f) was indistinguishable from SAPc(f). With the opened CSBR, intracarotid sinus pressure (CSP) was pseudorandomly varied, and the resulting SAP responses were recorded to determine the transfer function from CSP to SAP [HCSP.SAP(f)]. From SAPo(f) and the determined HCSP.SAP(f), we estimated SAP(f) if the CSBR was closed [SAPc,est(f)] and compared it with SAPc(f). These two spectra were similar in each dog over a frequency range of 0.002–0.15 Hz, the differences between SAPo(f) and SAPc(f) being reconcilable with HCSP.SAP(f). Although the anesthetized state and vagotomy may have distorted the transfer characteristics of the CSBR from those in conscious (with the intact vagi) states, the results of the present study indicate that the CSBR attenuated SAP variability mainly in a low-frequency range below 0.02 Hz and that this attenuation was attributable to the transfer properties of the CSBR.

Reduced carotid baroreceptor distensibility-induced baroreflex resetting contributes to impairment of sodium regulation in rats fed a high-fat diet

2015 ◽  
Vol 308 (8) ◽  
pp. H942-H950 ◽  
Author(s):  
Chikara Abe ◽  
Yuko Nagai ◽  
Aoi Yamaguchi ◽  
Hitomi Aoki ◽  
Shuji Shimizu ◽  
...  
Keyword(s):  
Carotid Artery ◽  
Common Carotid Artery ◽  
High Fat Diet ◽  
Open Loop ◽  
Sodium Balance ◽  
High Fat ◽  
Loop Analysis ◽  
Obese Subjects ◽  
The Common ◽  
Sodium Regulation

Decreased carotid arterial compliance has been reported in obese subjects and animals. Carotid baroreceptors are located at the bifurcation of the common carotid artery, and respond to distension of the arterial wall, suggesting that higher pressure is required to obtain the same distension in obese subjects and animals. A hyperosmotic NaCl solution induces circulatory volume expansion and arterial pressure (AP) increase, which reflexively augment renal excretion. Thus, we hypothesized that sodium regulation via the baroreflex might be impaired in response to chronic hyperosmotic NaCl infusion in rats fed a high-fat diet. To examine this hypothesis, we used rats fed a high-fat (Fat) or normal (NFD) diet, and measured mean AP, water and sodium balance, and renal function in response to chronic infusion of hyperosmotic NaCl solution via a venous catheter. Furthermore, we examined arterial baroreflex characteristics with static open-loop analysis and distensibility of the common carotid artery. Significant positive water and sodium balance was observed on the 1st day of 9% NaCl infusion; however, this disappeared by the 2nd day in Fat rats. Mean AP was significantly higher during 9% NaCl infusion in Fat rats compared with NFD rats. In the open-loop analysis of carotid sinus baroreflex, a rightward shift of the neural arc was observed in Fat rats compared with NFD rats. Furthermore, distensibility of the common carotid artery was significantly reduced in Fat rats. These results indicate that a reduced baroreceptor distensibility-induced rightward shift of the neural arc might contribute to impairment of sodium regulation in Fat rats.

scholarly journals Carotid-Sinus Baroreflex Modulation of Core and Skin Temperatures in Rats: An Open-Loop Approach

2003 ◽  
Vol 53 (6) ◽  
pp. 461-466 ◽  
Author(s):  
Dongmei Zhang ◽  
Motonori Ando ◽  
Fumiyasu Yamasaki ◽  
Takayuki Sato
Keyword(s):  
Carotid Sinus ◽  
Open Loop ◽  
Carotid Sinus Baroreflex ◽  
Skin Temperatures

Counteraction of aortic baroreflex to carotid sinus baroreflex in a neck suction model

2000 ◽  
Vol 89 (5) ◽  
pp. 1979-1984 ◽  
Author(s):  
Toru Kawada ◽  
Masashi Inagaki ◽  
Hiroshi Takaki ◽  
Takayuki Sato ◽  
Toshiaki Shishido ◽  
...  
Keyword(s):  
Animal Model ◽  
Arterial Pressure ◽  
Linear Model ◽  
Closed Loop ◽  
Carotid Sinus ◽  
Open Loop ◽  
Pressure Perturbation ◽  
Loop Gain ◽  
First Approximation ◽  
Carotid Sinus Baroreflex

Although neck suction has been widely used in the evaluation of carotid sinus baroreflex function in humans, counteraction of the aortic baroreflex tends to complicate any interpretation of observed arterial pressure (AP) response. To determine whether a simple linear model can account for the AP response during neck suction, we developed an animal model of the neck suction procedure in which changes in carotid distension pressure during neck suction were directly imposed on the isolated carotid sinus. In six anesthetized rabbits, a 50-mmHg pressure perturbation on the carotid sinus decreased AP by −27.4 ± 4.8 mmHg when the aortic baroreflex was disabled. Enabling the aortic baroreflex significantly attenuated the AP response (−21.5 ± 3.8 mmHg, P< 0.01). The observed closed-loop gain during simulated neck suction was well predicted by the open-loop gains of the carotid sinus and aortic baroreflexes using the linear model (−0.43 ± 0.13 predicted vs. −0.41 ± 0.10 measured). We conclude that the linear model can be used as the first approximation to interpret AP response during neck suction.

Sign in / Sign up

Export Citation Format

Share Document