Amplitude dependence of the carotid sinus reflex

Kenner, Thomas; Baertschi, Alex J.; Allison, James L.; Ono, Koichi

doi:10.1007/bf00592650

Cited by 10 publications

(5 citation statements)

References 4 publications

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“…Simulations of the mean arterial pressure response to a cardiac output perturbation in the dog, using the data of Table 1 together with values of natural frequency, damping factor and time constants of the windkessel load as found in the literature (Scher & Young, 1963; Levison et al , 1966; Suga & Oshima, 1971; Kenner et al 1974; Sagawa, 1979; Scher et al 1991; Burattini, 2001; Liu et al 2002), showed similar behaviour as the response in the cat.…”

Section: Resultsmentioning

confidence: 57%

“…To simulate the responses in the cat, mean arterial pressure was set at 140 mmHg and the cardiac output perturbation was chosen such that it caused a ΔP i of 24 mmHg. Natural pulsation and damping were given the values of ω n = 0.4 rad s −1 and ζ= 0.4, respectively (Scher & Young, 1963; Levison et al 1966; Suga & Oshima, 1971; Kenner et al 1974; Sagawa, 1979; Burattini et al 1987 b , d ; Scher et al 1991; Liu et al 2002). Windkessel parameters (eqn A3) were τ 1 = 1.1 s, τ 2 = 0.063 s, and R 0 = 0.54 mmHg min ml −1 (Burattini et al 1987 b ,d).…”

Section: Resultsmentioning

confidence: 99%

“…The dynamic performance of the baroreceptor reflex in dogs, cats and rabbits has been investigated in several studies (Scher & Young, 1963; Levison et al 1966; Suga & Oshima, 1971; Kenner et al 1974; Sagawa, 1979; Scher et al 1991; Liu et al 2002; Kawada et al 2003). Almost all investigations were performed on the carotid sinus reflex system.…”

Section: Discussionmentioning

confidence: 99%

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The baroreflex is counteracted by autoregulation, thereby preventing circulatory instability

Burattini

Borgdorff

Westerhof

2004

Experimental Physiology

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The aims of this study were (a) to apply in the animal with intact baroreflex a two-point methodforestimationofoverall,effectiveopen-loopgain, G 0e ,whichresultsfromthecombined action of baroregulation and total systemic autoregulation on peripheral resistance; (b) to predict specific baroreflex gain by correcting the effective gain for the autoregulation gain; and (c) to discuss why the effective gain is usually as low as 1-2 units. G 0e was estimated from two measurements of both cardiac output, Q, and mean systemic arterial pressure, P: one in the reference state (set-point) and the other in a steady-state reached 1-3 min after a small cardiac output perturbation. In anaesthetized cats and dogs a cardiac output perturbation was accomplished by partial occlusion of the inferior vena cava and by cardiac pacing, respectively. Average (± S.E.M.) estimates of G 0e were 1.4 ± 0.2 (n = 8) in the cat and 1.5 ± 0.4 (n = 5) in the dog. The specific baroreflex open-loop gain, G 0b , found after correction for total systemic autoregulation, was 3.3 ± 0.4 in the cat and 2.8 ± 0.8 in the dog. A model-based analysis showed that, with G 0e as low as 1.4, the closed-loop response of P to a stepwise perturbation in Q results in damped oscillations that disappear in about 1 min. The amplitude and duration of these oscillations, which have a frequency of about 0.1 Hz, increase with increasing G 0e and cause instability when G 0e is about 3. We conclude that autoregulation reduces the effectiveness of baroreflex gain by about 55%, thereby preventing instability of blood pressure response.

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Section: Resultsmentioning

confidence: 57%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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The baroreflex is counteracted by autoregulation, thereby preventing circulatory instability

Burattini

Borgdorff

Westerhof

2004

Experimental Physiology

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“…At first sight then, it is somewhat puzzling that neither average discharge rate nor any of the other receptor response parameters correlate consistently with pulse pressure even though it varied over wide ranges in our experiments. The explanation for this result comes from work by Stegemann & Tibes (1969), who convincingly showed that the reflex augmenting effect of pulse pressure over static pressure is related to the operating point chosen on the sigmoid reflex Kenner & Baertschi, 1974).…”

Section: Discussionmentioning

confidence: 97%

“…near threshold and in the saturation range. Since baroreceptors operate physiologically near their thresholds (Arndt et al 1974), where the average discharge rate is smaller for dynamic than for static stimulation of equal average value it is understandable why variations in the pulse pressure have a more pronounced reflex effect in this situation (Stegemann & Tibes, 1969;Kenner & Baertschi, 1974).…”

Section: Discussionmentioning

confidence: 99%

The physiologically relevant information regarding systemic blood pressure encoded in the carotid sinus baroreceptor discharge pattern.

Arndt¹,

Morgenstern²,

Samodelov³

1977

The Journal of Physiology

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SUMMARY1. The objective was to find out what kind of information regarding systemic blood pressure is transduced by baroreceptors in vivo and how this information is coded in the receptor discharge.2. Carotid sinus pressure, e.c.g., and receptor action potentials were recorded for fifty-two single fibre carotid sinus receptors found in twenty decerebrated unanaesthetized cats. 3. The inflation and gradual deflation of an intraaortic catheter tip balloon manipulated the blood pressure in the carotid sinus in a way as to define the full in vivo stimulus-response curve for each receptor.4. Correlation coefficients were computed between stimulus and response variables for several points on the response curve of each receptor and for every possible combination of stimulus and response variables defined.5. Stimulus variables were (a) systolic, (b) diastolic, (c) mean, (d) pulse pressures and (e) peak positive dP/dt. Response variables were (a) average discharge rate, (b) peak instantaneous frequency, and (c) average burst frequency.6. For every fibre in the sample only the correlations between systolic, diastolic and mean pressures vs. average discharge rate were consistently high and positive. All other correlations were numerically low and/or negative.7. It was concluded that in vivo baroreceptors signal mainly pressure level (systolic, diastolic or mean) as opposed to pulse pressure or dP/dt, and that the average discharge rate is their best index of information content.

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