Factors Influencing the Carotid Baroreceptor Response to Pressure Changes in a Neck Chamber

1976 ◽  
Vol 51 (s3) ◽  
pp. 347s-349s ◽  
Author(s):  
J. Ludbrook ◽  
G. Mancia ◽  
A. Ferrari ◽  
A. Zanchetti
Keyword(s):  
Carotid Sinus ◽  
Pressor Response ◽  
Baroreceptor Reflex ◽  
Chamber Pressure ◽  
Positive Pressure ◽  
Carotid Baroreceptor ◽  
Factors Influencing ◽  
Correct Analysis ◽  
Pressure Changes ◽  
Neck Chamber

1. Transmission of pneumatic pressure from a neck chamber to the region of the carotid sinus is imperfect and asymmetric (86% of positive pressure, 64% of negative pressure). This has to be taken into account in the correct analysis of the carotid baroreceptor reflex. 2. There is no evidence for a reduction in cerebral blood flow nor of carotid chemoreceptor stimulation in response to an increase in neck chamber pressure of about 45 mmHg. Thus it is likely that the pressor response to this manoeuvre is in fact due to reduction in carotid baroreceptor activity.

The Variable-Pressure Neck-Chamber Method for Studying the Carotid Baroreflex in Man

1977 ◽  
Vol 53 (2) ◽  
pp. 165-171 ◽  
Author(s):  
J. Ludbrook ◽  
G. Mancia ◽  
A. Ferrari ◽  
A. Zanchetti
Keyword(s):  
Negative Pressure ◽  
Carotid Sinus ◽  
Venous Blood ◽  
Baroreceptor Reflex ◽  
Variable Pressure ◽  
Positive Pressure ◽  
Chamber Method ◽  
Carotid Baroreceptor ◽  
Pressure Changes ◽  
Neck Chamber

1. The variable-pressure neck-chamber method was analysed in ten healthy volunteer subjects to determine its suitability for the study of the carotid baroreceptor reflex in man. 2. Positive and negative pressures applied to the neck (range ± 60 mmHg) were always transmitted linearly to a tissue catheter outside the carotid sinus, but only 86% of positive pressure, and 64% of negative pressure. Tissue pressures were confirmed by simultaneous measurement in the internal jugular vein adjacent to the carotid sinus. 3. Positive and negative pressure changes within the above range did not alter Po2 of internal jugular venous blood, suggesting that cerebral blood flow was unaltered. 4. Positive pressure changes induced reflex pressor responses of similar magnitude at arterial Po2 12·8 and 70·1 kPa (96 and 527 mmHg), suggesting that the carotid chemoreceptors were not involved. 5. It is concluded that the variable-pressure neck chamber is a valid method for selectively studying the carotid baroreceptor reflex in man. However, transmission of external pneumatic pressure to the carotid sinus is imperfect and greater for positive than for negative pressure. This must be recognized to avoid underestimation of gain and distortion of shape of the reflex.

Sympathetic transients caused by abrupt alterations of carotid baroreceptor activity in humans

1982 ◽  
Vol 242 (2) ◽  
pp. H185-H190 ◽  
Author(s):  
B. G. Wallin ◽  
D. L. Eckberg
Keyword(s):  
Sympathetic Activity ◽  
Chamber Pressure ◽  
Reduced Pressure ◽  
Cardiac Responses ◽  
Carotid Baroreceptor ◽  
Sympathetic Responses ◽  
Nerve Muscle ◽  
Neck Pressure ◽  
Pressure Changes ◽  
Neck Chamber

We examined the role of carotid baroreceptors in the short-term modulation of sympathetic outflow to the muscle vascular bed and parasympathetic outflow to the heart in 10 healthy adults. Afferent carotid baroreceptor activity was modified with 30-mmHg neck suction or pressure applied during held expiration, and efferent sympathetic activity was measured with microelectrodes inserted percutaneously into peroneal nerve muscle fascicles. Sympathetic responses were conditioned importantly by directional changes of carotid transmural pressure: increased pressure (onset of neck suction or offset of neck pressure) inhibited (totally) sympathetic activity, and reduced pressure (offset of neck suction or onset of neck pressure) augmented sympathetic activity. Responses occurred after a latency of about 2 s and did not persist as long as changes of neck-chamber pressure. Cardiac intervals were prolonged by increased carotid transmural pressures and shortened by decreased carotid transmural pressures, but, in contrast to sympathetic responses, cardiac responses adapted only slightly during neck-chamber pressure changes. Our results suggest that in the human a common baroreceptor input is processed differently in central vagal and sympathetic networks. Muscle sympathetic responses to changing levels of afferent baroreceptor traffic are profound but transitory. They appear to be conditioned more by changes of arterial pressure than by its absolute levels.

Continuous resetting of the human carotid baroreceptor-cardiac reflex

1987 ◽  
Vol 252 (4) ◽  
pp. R732-R736 ◽  
Author(s):  
G. A. Kasting ◽  
D. L. Eckberg ◽  
J. M. Fritsch ◽  
C. L. Birkett
Keyword(s):  
Arterial Pressure ◽  
Reflex Response ◽  
Chamber Pressure ◽  
Systematic Change ◽  
Circadian Changes ◽  
Ongoing Process ◽  
Carotid Baroreceptor ◽  
Pressure Changes ◽  
Neck Chamber ◽  
Human Carotid

Although human baroreflex responses have been studied during night as well as day, there has been no attempt to distinguish circadian changes of baroreflex function from those related to sleep. We measured carotid baroreceptor-cardiac reflex responses serially during a 24-h period in 11 normotensive volunteers who were awake and cooperative during testing. We applied sequences of ramped R-wave-triggered neck chamber pressure changes from +40 to -65 mmHg, during held expiration, at 3-h intervals. Subjects maintained their usual sleep-wake cycles but were awakened for three 30-min periods for night testing. There was no systematic change of baroreflex slope during the 24-h period. There were, however, parallel shifts of the entire sigmoid baroreceptor-cardiac reflex response relation along its R-R interval and arterial pressure axes associated with small, but significant, circadian changes of baseline R-R intervals and arterial pressures. Thus, although our data do not point toward major circadian variability of baro-reflex responsiveness, they provide evidence for an ongoing process of human baroreflex resetting.

Device for rapid quantification of human carotid baroreceptor-cardiac reflex responses

1986 ◽  
Vol 60 (2) ◽  
pp. 727-732 ◽  
Author(s):  
J. M. Sprenkle ◽  
D. L. Eckberg ◽  
R. L. Goble ◽  
J. J. Schelhorn ◽  
H. C. Halliday
Keyword(s):  
Reflex Response ◽  
Chamber Pressure ◽  
Pressure System ◽  
New Device ◽  
Reflex Responses ◽  
Carotid Baroreceptor ◽  
Human Volunteers ◽  
Pressure Changes ◽  
Neck Chamber ◽  
Human Carotid

We designed, constructed, and evaluated a new device to characterize the human carotid baroreceptor-cardiac reflex response relation rapidly. We designed this system for study of reflex responses of astronauts before, during, and after space travel. The system comprises a new tightly sealing silicone rubber neck chamber, a stepping motor-driven electro-deposited nickel bellows pressure system, capable of delivering sequential R-wave-triggered neck chamber pressure changes between +40 and -65 mmHg, and a microprocessor-based electronics system for control of pressure steps and analysis and display of responses. This new system provokes classic sigmoid baroreceptor-cardiac reflex responses with threshold, linear, and saturation ranges in most human volunteers during one held expiration.

Plasma Catecholamines do Not Invariably Reflect Sympathetically Induced Changes in Blood Pressure in Man

1983 ◽  
Vol 65 (3) ◽  
pp. 227-235 ◽  
Author(s):  
G. Mancia ◽  
A. Ferrari ◽  
Luisa Gregorini ◽  
G. Leonetti ◽  
G. Parati ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Sympathetic Activity ◽  
Pressor Response ◽  
Plasma Concentrations ◽  
Plasma Catecholamines ◽  
Plasma Noradrenaline ◽  
Carotid Baroreceptor ◽  
Induced Changes ◽  
Neck Chamber ◽  
Noradrenaline And Adrenaline

1. Plasma concentrations of noradrenaline and adrenaline were measured radioenzymatically in nine subjects during 4 min pressor and depressor responses (intra-arterial measurements) induced by increasing and reducing sympathetic vasoconstrictor tone via carotid baroreceptor deactivation and stimulation (neck chamber technique). 2. During the pressor response (15 ± 3 mmHg, mean ± se) plasma noradrenaline and adrenaline showed various changes in the different subjects and on average were not significantly increased above control. During the depressor response (−9 ± 2 mmHg) plasma noradrenaline and adrenaline also showed various changes in the subjects and were on average not significantly reduced below control. 3. In contrast the same subjects all showed an increase in noradrenaline and adrenaline (average 76 and 117%) at the fourth minute of a tilting manoeuvre with- a return to pretilting values no more than 4 min after resumption of the supine position. 4. These results suggest that the moderate and/or restricted alterations in sympathetic tone produced by manipulating a single baroreflex, though capable of affecting blood pressure, are not reflected by alterations in plasma catecholamines. To modify these humoral indices significantly, the more drastic or more diffuse alterations in sympathetic activity that may be produced by manipulating low as well as high pressure reflexogenic areas are needed.

Characterization of the Sympatho-Facilitative Area Postrema Pathway

1980 ◽  
Vol 59 (s6) ◽  
pp. 255s-257s ◽  
Author(s):  
Karen L. Barnes ◽  
C. M. Ferrario
Keyword(s):  
Electrical Stimulation ◽  
Carotid Sinus ◽  
Area Postrema ◽  
Pressor Response ◽  
Baroreceptor Reflex ◽  
Solitary Tract ◽  
Anatomical Studies ◽  
Solitary Complex ◽  
Stimulation Of

1. The mechanism by which the area postrema augments central sympathetic drive during electrical stimulation is presently unknown. This pathway may involve either direct facilitation of brain-stem vasomotor neurons or inhibition of the sympatho-inhibitory baroreceptor relay in the nucleus tractus solitarii. 2. The present study employed selective lesions within the solitary tract nucleus to assess the participation of the primary baroreceptor relay in the pressor response during electrical stimulation of the area postrema. 3. The magnitude of the pressor response was unchanged after destruction of the solitary tract and lateral solitary nucleus which centrally interrupted the baroreceptor reflex. However, microknife cuts through the medial solitary nucleus, which spared the carotid sinus reflex, significantly reduced the magnitude of the area postrema pressor response. 4. Previous anatomical studies support these results and confirm that, although the area postrema pressor pathway traverses the most medial portion of the solitary complex, it does not produce augmented sympathetic outflow by inhibition of the primary baroreflex relay.

Central neural regulation of carotid baroreceptor reflexes in the cat

1965 ◽  
Vol 209 (6) ◽  
pp. 1267-1277 ◽  
Author(s):  
Donald J. Reis ◽  
Michel Cuenod
Keyword(s):  
Carotid Sinus ◽  
Pressor Response ◽  
Brain Structures ◽  
Carotid Occlusion ◽  
Carotid Baroreceptor ◽  
Pressor Responses ◽  
Baroreceptor Reflexes ◽  
Aortic Blood Pressure ◽  
The Mean ◽  
Stimulation Of

Reflex changes of the mean aortic blood pressure (BP) to carotid sinus stretch or carotid occlusion in anesthetized vagotomized cats were observed following ablation or electrical stimulation of brain. Decerebration produced augmentation of the depressor response to sinus stretch, reduction of the pressor response to carotid occlusion, and fall of BP. Subsequent cerebellectomy produced an increase of depressor and pressor responses. Midpontine section produced disappearance of the pressor response to carotid occlusion and appearance of a "paradoxical" pressor response to sinus stretch. Stimulation within hypothalamus and reticular formation produced augmentation and a barbiturate-sensitive poststimulus depression of pressor response without changes in BP. It is concluded that baroreceptor reflex responsiveness is under tonic and phasic control of brain structures above medulla and that pressor and depressor limbs of the reflex are not reciprocal and modified independently of each other and of the BP. This suggests functional separation of brainstem neurons involved in reflex and tonic BP control and that some cerebral regulation of BP is indirectly mediated through vascular reflexes.

Rapid resetting of the carotid baroreceptor reflex in the cat

1981 ◽  
Vol 241 (6) ◽  
pp. H802-H806 ◽  
Author(s):  
D. L. Kunze
Keyword(s):  
Carotid Sinus ◽  
Blood Pressure Response ◽  
Systemic Blood Pressure ◽  
Baroreceptor Reflex ◽  
Reflex Response ◽  
Carotid Baroreceptor ◽  
Depressor Reflex ◽  
Sinus Pressure ◽  
Anesthetized Cat

The carotid baroreceptor depressor reflex of the chloralose-anesthetized cat was examined to determine the role of the prevailing carotid pressure in determining the threshold, gain, and range of operation of the reflex response. After the pressure of an isolated perfused carotid sinus was held at 80 mmHg for 20 min the threshold pressure necessary to elicit the reflex systemic blood pressure response was 78 +/- 2.9 (SE) mmHg (n = 5). When carotid pressure was maintained for 20 min at 120 and 160 mmHg the threshold rose to 113 +/- 2.9 and 126 +/- 3.0 mmHg, respectively. The resetting of the threshold to a stable value upon elevating or reducing carotid sinus pressure was accomplished within 15—;20 min. The entire range of operation of the reflex response was shifted to higher carotid pressures as the holding pressure was elevated. The midrange gain of the response was unchanged at the three holding pressures tested. These findings indicate that the carotid baroreceptor reflex need not operate over a fixed range but that the range may be rapidly adjustable to the prevailing pressure. When arterial pressure is sustained at a level that is elevated or depressed from normal the carotid baroreceptor reflex acutely resets to operate in the range of the prevailing pressure with a threshold that has moved toward the prevailing pressure.

Modeling of arterial and cardiopulmonary baroreflex control of heart rate

1997 ◽  
Vol 272 (5) ◽  
pp. H2343-H2352 ◽  
Author(s):  
T. H. Desai ◽  
J. C. Collins ◽  
M. Snell ◽  
R. Mosqueda-Garcia
Keyword(s):  
Aortic Arch ◽  
Carotid Sinus ◽  
Lower Body Negative Pressure ◽  
Venous Pressure ◽  
Chamber Pressure ◽  
Baroreflex Control ◽  
Cardiopulmonary Baroreflex ◽  
Phenylephrine Infusion ◽  
Cardiopulmonary Receptors ◽  
Pressure Changes

We evaluated R-R interval changes (delta R-R interval) in 13 subjects (27 +/- 6 yr; 7 men and 6 women) as a function of blood pressure changes at the carotid sinus and aortic arch and central venous pressure changes at the cardiopulmonary receptors. Neck chamber pressure and suction were used to change pressure at the carotid sinus while lower body negative pressure, phenylephrine infusion, and nitroprusside infusion were used to change pressure at the carotid sinus (delta CSP), aortic arch (delta AAP), and cardiopulmonary receptors (delta CPP). Random effects regression analysis showed a significant linear relationship for delta R-R interval (-1.75 + 1.64 delta CSP + 15.40 delta AAP + 29.02 delta CPP + error), and the correlation (r) between the observed and predicted delta R-R interval was 0.82 (P < 0.00001). Sixty-seven percent of the delta R-R interval variability observed in the study is explained by the model. delta AAP accounts for approximately 63%, delta CSP for 14%, and delta CPP for 23% of the explained delta R-R interval.

Carotid Baroreceptor Reflex in Normotensive and Hypertensive Subjects

1976 ◽  
Vol 51 (s3) ◽  
pp. 343s-345s ◽  
Author(s):  
G. Mancia ◽  
J. Ludbrook ◽  
A. Ferrari ◽  
L. Gregorini ◽  
R. Valentini ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Baroreceptor Reflex ◽  
The Other ◽  
Reflex Response ◽  
Arterial Blood ◽  
Carotid Baroreceptor ◽  
Normotensive Subjects ◽  
Neck Chamber ◽  
Related Increase

1. A graded decrease and increase in carotid baroreceptor activity (induced by a varying pressure in a neck chamber) caused a linearly related increase and decrease in arterial blood pressure. This occurred in both normotensive and hypertensive subjects. 2. Decrease of carotid baroreceptor activity caused a greater increase of blood pressure in normotensive than in hypertensive subjects. Increasing the activity caused changes of similar magnitude in the two groups. 3. Decrease of baroreceptor activity also caused an increase in heart rate although increasing the activity of the reflex had little effect on heart rate, particularly in normotensive subjects. Thus the carotid baroreceptor effect on blood pressure does not always reflect that on heart rate and inference of one reflex response from measurement of the other may be in error.

Sign in / Sign up

Export Citation Format

Share Document