The contribution of alterations in cardiac output to changes in arterial pressure reflexly evoked from the carotid sinus in the rabbit.

Humphreys, P. W.; Joels, N.

doi:10.1113/jphysiol.1977.sp011743

Cited by 11 publications

(10 citation statements)

References 16 publications

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“…The characteristics of our stimulus-response curves for blood pressure are very similar to those derived from preparations of an isolated carotid sinus in anaesthetized rabbits by Koch (1929Koch ( , 1931 and Humphreys & Joels (1977). Humphreys and Joels' data suggest a maximum gain of just less than 1 mmHg/mmHg and a range of 68 mmHg, and similar values can be inferred from Koch's work.…”

Section: Discussionsupporting

confidence: 73%

“…Gross & Kirchheim (1972) showed in the conscious dog that cardiac pacing did not alter the magnitude of the pressor response to common carotid artery occlusion. Humphreys & Joels (1977) demonstrated that in the anaesthetized rabbit cardiac output (and thus heart rate) contributed much less than peripheral resistance to reflex alteration of blood pressure by the carotid sinus. This suggests that a change in the sensitivity of baroreceptor control of heart rate may not always be associated with a corresponding change in the control of blood pressure.…”

Section: Discussionmentioning

confidence: 99%

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The carotid sinus baroreceptor reflex in conscious rabbits.

Faris¹,

Iannos²,

Jamieson³

et al. 1980

The Journal of Physiology

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SUMMARY1. A method is described for altering the pressure across the wall of the carotid sinus in conscious rabbits by enclosing the carotid bifurcation in a rigid, fluid-filled capsule. The extracapsular arterial baroreceptors were denervated.2. The baroreceptor-heart rate reflex, elicited by injecting vasoactive drugs or inflating aortic and vena caval cuffs, was used to test the new method. The function of the carotid sinus was shown to be unaffected by enclosure in the capsule. Denervation of the extracapsular baroreceptors reduced the gain of the baroreceptor-heart rate reflex two-to threefold.3. The characteristics of the carotid baroreceptor reflex were studied in sixteen animals by the capsule method. Median estimates of maximum gain, and the range over which blood pressure changed, were 1 1 mmHg/mmHg and 57 mmHg respectively. There was good agreement between duplicate estimates made 1-20 days apart.4. There was only a weak association between the effects on blood pressure and heart rate of altering carotid sinus transmural pressure. Autonomic blockade of the heart, so that its rate was fixed, did not reduce the gain or range of blood pressure change.

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Section: Discussionsupporting

confidence: 73%

Section: Discussionmentioning

confidence: 99%

The carotid sinus baroreceptor reflex in conscious rabbits.

Faris¹,

Iannos²,

Jamieson³

et al. 1980

The Journal of Physiology

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“…A moderate increase of cardiac output had been observed already in the relatively early stages of the side pressure exertion experiment (Takeuchi and Miyakawa, recently submitted). HUMPHREYS and JOELS (1977) also observed an increase of cardiac output at the initial phase of the cerebral ischemic reaction. Since the flow in the isolated circuits was held constant, an increase flow in the systemic circulation would give a greater pressure for the same degree of resistance change.…”

Section: Discussionmentioning

confidence: 81%

Vascular Resistance of Intestine, Muscle and Skin during Blood Pressure Oscillation

1979

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After the blood supply to the head was surgically limited to one common carotid artery in rabbits, the artery was compressed by exertion of stepwise elevated side pressure on a segment of the artery. Systemic arterial pressure rose and began to oscillate when the side pressure was increased to 50 to 60 mmHg. The oscillations were regular and occurred at a rate of 3 to 4 per minute with a wave height of 15 to 45 mmHg. Concomitant with systemic pressure oscillations, and in near synchrony were undulations in the perfusion pressures recorded during constant flow from the vascularly isolated abdominal skin, skeletal muscle and small intestine. With the graded elevation of side pressure on the common carotid artery, mean systemic pressure and perfusion pressure showed a nearly exponential relation. The ratio between the two variables was slightly less than one below the systemic pressure of 120 mmHg and rapidly increased above this level. At ratios greater than one, the peripheral resistance undulations in the isolated areas gave a larger minimum and maximum, a sharper contour and, particularly in the skin, a phase lag in the period of the wave form when compared to the systemic pressure oscillations. These observations highlight the differences in response characteristics of peripheral resistance vessels and those of cardiac output and different consecutive parts of the systemic arteries during periods of intense sympathetic activation.In 1901, CUSHING (1901) observed a blood pressure oscillation in the process of a stepwise elevation of cerebrospinal fluid pressure in dogs. From that time, several investigators (GUYTON and SATTERFIELD, 1952; SAGAWA et al., 1961 a, b) have studied "central nervous system ischemic reflex oscillation" as named by GUYTON and SATTERFIELD (1952). MIYAKAWA (1966 a, b) devised a method for elicitation of a blood pressure oscillation in rabbits, by graded compression of a common carotid artery which was left as the only route of blood supply to the brain. We call this experiment the "side pressure exertion experiment." Thereafter, a number

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“…Thermal dilution has been compared with the direct Fick and dye dilution techniques in the dog (Goodyer, Huvos, Eckhardt & Ostberg, 1959;Wessel, Paul, James & Grahn, 1971) and with dye dilution in the rabbit (Korner, 1965;Warren & Ledingham, 1974;Humphreys & Joels, 1977). Correlation coefficients of the order of 0-96 were reported, though Warren & Ledingham (1974) reported a poor correlation between thermal and dye dilution in conscious rabbits at low circulating volumes.…”

Section: Methodsmentioning

confidence: 99%

Haemodynamic responses to stimulation of the cardiac autonomic nerves in the anaesthetized cat with closed chest

Barnes

Bower

Rink

1980

The Journal of Physiology

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SUMMARY1. The changes in cardiac output and mean right atrial pressure (R.A.P.) evoked by stimulation of the cardiac autonomic nerves were investigated in cats under chloralose anaesthesia, with unopened chests and spontaneous respiration, and with active vascular reflexes. Cardiac output was measured by thermal dilution; the technique used was calibrated against the direct Fick method.2. The initial values of R.A.P. and output were varied by infusion of dextran-saline solution followed by withdrawal of blood. At positive values of R.A.P. withdrawal of blood caused a fall in R.A.P. with no change in cardiac output. At negative R.A.P. blood withdrawal caused a fall in output with little change in R.A.P.: the linear regression coefficient for output on R.A.P. was 48-2 ml./min.kg.mmHg (s.E. 2-06, n = 63, nine cats).3. Stimulation of the right cardiac sympathetic nerve increased heart rate by 69*2 beats/min (S.E. 4.0) from the resting rate of 158 beats/min (S.E. 6-3, ten cats).The acceleration was accompanied in most instances by a rise in cardiac output and a fall in R.A.P. and the magnitude of the rise in output was related to that of the fall in R.A.P.4. In no experiment could R.A.P. be reduced below -2-5 mmHg either by withdrawal of blood or by sympathetic stimulation. At negative values of R.A.P. the fall in R.A.P. and rise in output evoked by sympathetic stimulation were small; substantial changes could be obtained only from positive initial values of R.A.P. The proportional increase in output evoked by a given proportional increase in heart rate during near-maximal sympathetic stimulation had a linear relationship to the initial value of R.A.P. over the range -2 to + 8 mmHg. The output increment was less than proportional to the rate increment at all values of R.A.P. below + 3 mmHg.5. In five experiments stimulation of the left cardiac sympathetic nerve evoked a greater increase in output for a given increase in heart rate than did stimulation of the right nerve; on the other hand both nerves gave similar increments of output for a given fall in R.A.P.6. Stimulation of the distal end of the right vagus nerve slowed the heart and caused a fall in cardiac output and a rise in R.A.P. The change in output associated with a given change in R.A.P. was significantly greater (P = 0.05) during sympathe- 0022-3751/80/6880-0013 $07.50

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The contribution of alterations in cardiac output to changes in arterial pressure reflexly evoked from the carotid sinus in the rabbit.

Cited by 11 publications

References 16 publications

The carotid sinus baroreceptor reflex in conscious rabbits.

The carotid sinus baroreceptor reflex in conscious rabbits.

Vascular Resistance of Intestine, Muscle and Skin during Blood Pressure Oscillation

Haemodynamic responses to stimulation of the cardiac autonomic nerves in the anaesthetized cat with closed chest

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