Role of active changes in venous capacity by the carotid baroreflex: analysis with a mathematical model

1994 ◽  
Vol 267 (6) ◽  
pp. H2531-H2546 ◽  
Author(s):  
M. Ursino ◽  
M. Antonucci ◽  
E. Belardinelli
Keyword(s):  
Mathematical Model ◽  
Arterial Pressure ◽  
Cardiovascular System ◽  
Carotid Sinus ◽  
Regulatory Mechanisms ◽  
Unstressed Volume ◽  
Carotid Sinus Baroreflex ◽  
Left And Right ◽  
Venous Capacity

To elucidate the role of venous capacity active changes in short-term cardiovascular homeostasis, a mathematical model of the carotid-sinus baroreflex system has been developed. In the model the cardiovascular system is represented as the series arrangement of six lumped compartments, which synthesize the fundamental hemodynamic properties of the systemic arterial, systemic venous, pulmonary arterial, and pulmonary venous circulations as well as of the left and right cardiac volumes. Cardiac outputs from the left and right ventricles are computed as a function of both downstream arterial pressure (afterload) and upstream atrial pressure (preload). Four distinct feedback regulatory mechanisms, working on systemic arterial resistance, heart rate, systemic venous unstressed volume, and systemic venous compliance, are assumed to operate on the cardiovascular system in response to carotid sinus pressure changes. All model parameters, both in the cardiovascular system and in feedback regulatory mechanisms, have been assigned on the basis of physiological data now available. The model is used here to simulate the pattern of the main hemodynamic quantities in the short time period (1-2 min) after acute carotid sinus activation in vagotomized subjects. Simulation results indicate that the model can reproduce experimental data quite well, with reference both to open-loop experiments and to an acute blood hemorrhage performed in closed-loop conditions. Moreover, computer simulations indicate that active changes in venous unstressed volume are of primary importance in regulating cardiac output and systemic arterial pressure during activation of the carotid sinus baroreflex.

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.

Inhibition of NO synthesis minimally affects the dynamic baroreflex regulation of sympathetic nerve activity

1997 ◽  
Vol 272 (5) ◽  
pp. H2446-H2452 ◽  
Author(s):  
H. Miyano ◽  
T. Kawada ◽  
T. Shishido ◽  
T. Sato ◽  
M. Sugimachi ◽  
...  
Keyword(s):  
Transfer Function ◽  
Arterial Pressure ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Carotid Sinus ◽  
Function Analysis ◽  
Corner Frequency ◽  
Nerve Activity ◽  
Carotid Sinus Baroreflex ◽  
Transfer Function Analysis

The purpose of this investigation was to examine the role of nitric oxide (NO) in the dynamic baroreflex regulation of cardiac sympathetic nerve activity. In anesthetized rabbits, we imposed random pressure perturbations on the isolated carotid sinuses before and after the intravenous administration of NG-monomethyl-L-arginine. We characterized the dynamic properties relating carotid sinus pressure input to sympathetic nerve activity by means of a transfer function analysis. NG-monomethyl-L-arginine decreased the corner frequency of the transfer function (0.100 +/- 0.054 vs. 0.074 +/- 0.035 Hz; P < 0.05), whereas other parameters such as the steady-state gain and transmission lag time remained unchanged. Although cursory examination of these findings would suggest a possible contribution of NO in the dynamic baroreflex regulation of sympathetic nerve activity, quantitative assessment of the transfer function reveals only a minimal effect on the baroreflex regulation of arterial pressure, particularly under closed-loop conditions. We conclude that NO noticeably affects the dynamic baroreflex regulation of sympathetic nerve activity. However, it may not significantly affect arterial pressure regulation through central modulation of the carotid sinus baroreflex.

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 Total Effective Vascular Compliance of a Global Mathematical Model for the Cardiovascular System

Symmetry ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1858
Author(s):  
Morena Celant ◽  
Eleuterio F. Toro ◽  
Lucas O. Müller
Keyword(s):  
Mathematical Model ◽  
Cardiovascular System ◽  
Regulatory Mechanisms ◽  
Loop Model ◽  
Infusion Test ◽  
Total Blood ◽  
Hyperbolic Pde ◽  
Vascular Compliance ◽  
Arteries And Veins ◽  
Effective Vascular Compliance

In this work, we determined the total effective vascular compliance of a global closed-loop model for the cardiovascular system by performing an infusion test of 500 mL of blood in four minutes. Our mathematical model includes a network of arteries and veins where blood flow is described by means of a one-dimensional nonlinear hyperbolic PDE system and zero-dimensional models for other cardiovascular compartments. Some mathematical modifications were introduced to better capture the physiology of the infusion test: (1) a physiological distribution of vascular compliance and total blood volume was implemented, (2) a nonlinear representation of venous resistances and compliances was introduced, and (3) main regulatory mechanisms triggered by the infusion test where incorporated into the model. By means of presented in silico experiment, we show that effective total vascular compliance is the result of the interaction between the assigned constant physical vascular compliance and the capacity of the cardiovascular system to adapt to new situations via regulatory mechanisms.

Maintenance of carotid baroreflex function in advanced age in the rat

1986 ◽  
Vol 250 (6) ◽  
pp. R1047-R1051 ◽  
Author(s):  
J. Y. Wei ◽  
D. Mendelowitz ◽  
N. Anastasi ◽  
J. W. Rowe
Keyword(s):  
Arterial Pressure ◽  
Rat Model ◽  
Carotid Sinus ◽  
Pressure Response ◽  
Age Difference ◽  
Base Line ◽  
Fischer 344 ◽  
Baroreflex Function ◽  
Carotid Sinus Baroreflex ◽  
Fischer 344 Rat

To evaluate the influence of age per se on the carotid sinus baroreceptors in the absence of hypertension and atherosclerosis, we employed the Fischer 344 rat model. In 14 adult (A, 6-9 mo) and 9 senescent (S, 24-26 mo) normotensive male Fischer 344 rats the left carotid sinus region was vascularly isolated with sinus nerve intact and perfused with oxygenated modified Kreb's solution. Simultaneous measurements of intrasinus pressure and femoral arterial pressure response were obtained during linear pressure increases (20-200 mmHg) in the vascularly isolated sinus. There was no age difference in base-line arterial pressure or heart rate. Both age groups demonstrated similar positive relations between basal femoral arterial pressure and the magnitude of the femoral pressure response to equivalent carotid sinus pressures. There were similar estimated sinus volumes at onset of systemic response (39 +/- 1, A; 39 +/- 1 microliter, S), time to initial systemic pressure response (9 +/- 1, A; 7 +/- 1 s, S), mean rates of femoral pressure decline (1.8 +/- 0.3, A; 2.1 +/- 0.3 mmHg/s, S), and return to base line (1.5 +/- 0.3, A; 1.4 +/- 0.3 mmHg/s, S) as well as magnitudes of systolic (25 +/- 3, A; 26 +/- 4 mmHg, S) and diastolic (21 +/- 2 A; 22 +/- 4 mmHg, S) pressure drops. Thus, in the Fischer 344 rat model of aging, which differs from the human in that it is not complicated by hypertension or atherosclerosis, carotid sinus baroreflex function appears to be well maintained in senescence.

Peripheral versus central effect of intravenous moxonidine on rat carotid sinus baroreflex-mediated sympathetic arterial pressure regulation

Life Sciences ◽  
2017 ◽  
Vol 190 ◽  
pp. 103-109 ◽  
Author(s):  
Toru Kawada ◽  
Shuji Shimizu ◽  
Hiromi Yamamoto ◽  
Tadayoshi Miyamoto ◽  
Toshiaki Shishido ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Carotid Sinus ◽  
Central Effect ◽  
Pressure Regulation ◽  
Carotid Sinus Baroreflex ◽  
Arterial Pressure Regulation
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