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.

Peripheral vascular responses during carotid baroreceptor stimulation in normotensive and hypertensive subjects

1987 ◽  
Vol 73 (6) ◽  
pp. 635-640 ◽  
Author(s):  
D. Duprez ◽  
N. De Pue ◽  
D. L. Clement
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Essential Hypertension ◽  
Blood Vessels ◽  
Venous Occlusion ◽  
Peripheral Vascular ◽  
Carotid Baroreceptors ◽  
Arterial Blood ◽  
Carotid Baroreceptor ◽  
Normotensive Subjects

1. The carotid baroreceptors were stimulated for 2 min by neck suction at −30 and −60 mmHg in 19 normotensive subjects and 12 patients with moderate essential hypertension. 2. Blood pressure was measured with a mercury sphygmomanometer and heart rate was derived from beat-to-beat analysis of the electrocardiogram. Blood flow was measured simultaneously at calf and finger with venous occlusion plethysmography and the vascular resistance was calculated. 3. During neck suction at − 30 and − 60 mmHg there was a significant decrease in arterial blood pressure and heart rate. There was a transient vasodilatation of the calf blood vessels, while there was a sustained vasoconstriction of the finger blood vessels. These results were qualitatively similar in both groups; however, there were quantitative differences. 4. These experiments show that there is a selective autonomic control of the different peripheral vascular beds by the carotid baroreceptors in both normotension and mild essential hypertension.

Mechanism of circulatory responses to systemic hypoxia in the anesthetized dog

1965 ◽  
Vol 209 (2) ◽  
pp. 397-403 ◽  
Author(s):  
Hermes A. Kontos ◽  
H. Page Mauck ◽  
David W. Richardson ◽  
John L. Patterson
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cardiac Output ◽  
Vascular Resistance ◽  
The Other ◽  
Arterial Flow ◽  
Arterial Blood ◽  
Systemic Hypoxia ◽  
Anesthetized Dogs ◽  
Spontaneously Breathing

The possibility that mechanisms secondary to the increased ventilation may contribute significantly to the circulatory responses to systemic hypoxia was explored in anesthetized dogs. In 14 spontaneously breathing dogs systemic hypoxia induced by breathing 7.5% oxygen in nitrogen increased cardiac output, heart rate, mean arterial blood pressure, and femoral arterial flow, and decreased systemic and hindlimb vascular resistances. In 14 dogs whose ventilation was kept constant by means of a respirator pump and intravenous decamethonium, systemic hypoxia did not change cardiac output, femoral arterial flow, or limb vascular resistance; it significantly decreased heart rate and significantly increased systemic vascular resistance. In seven spontaneously breathing dogs arterial blood pCO2 was maintained at the resting level during systemic hypoxia. The increase in heart rate was significantly less pronounced but the other circulatory findings were not different from those found during hypocapnic hypoxia. Thus, mechanisms secondary to increased ventilation contribute significantly to the circulatory responses to systemic hypoxia. Hypocapnia accounts partly for the increased heart rate, but not for the other circulatory responses.

Regulation of Cardiac Output during 2,4-Dinitrophenol-Induced Tissue Hypermetabolism in the Dog

1977 ◽  
Vol 53 (1) ◽  
pp. 17-25
Author(s):  
C. Liang ◽  
W. B. Hood
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cardiac Output ◽  
Arterial Blood Pressure ◽  
Venous Blood ◽  
The Other ◽  
Pulmonary Artery Wedge Pressure ◽  
Systemic Arterial Blood Pressure ◽  
Arterial Blood ◽  
Wedge Pressure

1. Cardiac output increased in proportion to oxygen consumption in intact chloralose-anaesthetized dogs after four successive intravenous infusions of 2,4-dinitrophenol (11 μmol/kg; 2 mg/kg). 2. Splenectomy abolished the increase in cardiac output after the first three doses of 2,4-dinitrophenol. β-Adrenoreceptor blockade by practolol, on the other hand, did not prevent the cardiac output rise after the first 2,4-dinitrophenol infusion, but further increases by 2,4-dinitrophenol infusion were abolished. When splenectomy and β-adrenoreceptor blockade were combined, cardiac output did not increase significantly after all four doses of 2,4-dinitrophenol. 3. Cardiac output and mean systemic arterial blood pressure increased when the splenic venous blood collected after 2,4-dinitrophenol infusion was infused intraportally. 4. In a vascularly isolated, but normally innervated, lower half-body cross-perfusion preparation, cardiac output and mean systemic arterial blood pressure increased in the upper half-body when tissue hypermetabolism was produced in the cross-perfused area by 2,4-dinitrophenol. Neither pulmonary artery wedge pressure nor heart rate changed significantly. 5. This circulatory stimulation, after regional 2,4-dinitrophenol infusion, was abolished or was prevented from occurring by splenectomy. 6. It appears that the normal cardiac output response to tissue hypermetabolism requires both an intact spleen and normally functioning β-adrenoreceptors.

scholarly journals Alterations in the Baroreceptor-Heart Rate Reflex in Conscious Inbred Polydipsic (STR/N) Mice

2015 ◽  
pp. 173-182
Author(s):  
C. P. CHU ◽  
B. R. CUI ◽  
H. KANNAN ◽  
D. L. QIU
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Arterial Blood Pressure ◽  
Mean Arterial Blood Pressure ◽  
Cardiovascular Responses ◽  
Baroreceptor Reflex ◽  
Central Administration ◽  
Icr Mice ◽  
Arterial Blood ◽  
And Control

STR/N is an inbred strain of mice which is known to exhibit extreme polydipsia and polyuria. We previously found central administration of angiotensin II enhanced cardiovascular responses in STR/N mice than normal mice, suggesting that STR/N mice might exhibit different cardiovascular responses. Therefore, in this study, we investigated daily mean arterial blood pressure and heart rate, and changes in the baroreceptor-heart rate reflex in conscious STR/N mice and control (ICR) mice. We found that variability in daily mean arterial blood pressure and heart rate was significantly larger in STR/N mice than in ICR mice (p<0.05). There was a stronger response to phenylephrine (PE) in STR/N mice than in ICR mice. For baroreceptor reflex sensitivity, in the rapid response period, the slopes of PE and sodium nitroprusside (SNP) were more negative in STR/N mice than in ICR mice. In the later period, the slopes of PE and SNP were negatively correlated between heart rate and blood pressure in ICR mice, but their slopes were positively correlated in STR/N mice. These results indicated that STR/N mice exhibited the different cardiovascular responses than ICR mice, suggesting that the dysfunction of baroreceptor reflex happened in conscious STR/N mice.

Blood Volume and the Carotid Baroreceptor Reflex in Conscious Rabbits

1981 ◽  
Vol 61 (s7) ◽  
pp. 173s-175s ◽  
Author(s):  
J. Ludbrook ◽  
I. B. Faris ◽  
G. G. Jamieson
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cardiac Output ◽  
Systemic Vascular Resistance ◽  
Blood Volume ◽  
Vascular Resistance ◽  
Baroreceptor Reflex ◽  
Phase Lag ◽  
Carotid Baroreceptor ◽  
Conscious Rabbits

1. The effects of acute blood volume change in conscious rabbits on a.c. gain of the carotid baroreceptor reflex with respect to heart rate, blood pressure, cardiac output and systemic vascular resistance were studied. 2. With acute, isohaemic increase in blood volume by 20% and 40% the only consistent trend was a decrease in gain for systemic vascular resistance. 3. With acute reduction in blood volume there was a consistent tendency for gain for heart rate to fall. With 20% reduction in blood volume, gain for cardiac output fell but gain for systemic vascular resistance rose and its phase-lag became shorter, so that gain for blood pressure was unaltered. The enhanced gain for systemic vascular resistance was not sustained with 35% reduction in blood volume, so that gain for blood pressure fell. 4. Thus control of blood pressure by the carotid sinus reflex is remarkably unaffected by acute change in blood volume, and is impaired only when there is depression of gain for cardiac output without a concomitant rise in gain for systemic vascular resistance.

Comparison of Controlled Hypotension Due to the Use of Dexmedetomidine, Magnesium Sulfate, and Esmolol in Craniotomy Surgery

2021 ◽  
Vol 19 (12) ◽  
pp. 44-49
Author(s):  
Seyed Ali Ahmadi ◽  
Behnam Mahmodiyeh ◽  
Alireza Farsi ◽  
Alireza Kamali
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Magnesium Sulfate ◽  
Statistical Significance ◽  
The Other ◽  
Controlled Hypotension ◽  
Double Blind ◽  
Arterial Blood ◽  
Significant Difference ◽  
Bleeding Score

Introduction: Craniotomy includes the temporary removal of bone flap from calvarium to access the intracranial contents, which is usually used to reduce intracranial pressure. Induced or controlled hypotension is a method by which arterial blood pressure is predictably reduced, thus reducing bleeding. Therefore, the present study aimed to compare the dexmedetomidine, magnesium sulfate, and esmolol in controlled hypotension in craniotomy of patients with brain injury. Materials and methods: In this randomized double-blind clinical trial, 45 patients entered into study based on inclusion criteria. All patients were monitored when entering operating room. The questionnaire was completed by all groups, in which PR, MAP (Mean Arterial Pressure), mean bleeding score, mean of received packed cells, controlled hypotension and bradycardia, and survival of patients were recorded. Data were analyzed using spss software version 19, and ANOVA and T-Test were used for statistical significance analysis. Results: The mean age and standard deviations of the three groups of dexmedetomidine, esmolol and magnesium sulfate were 36.78±10.32, 34.47±10.58, and 39.67±11.99 years, respectively. There was no significant difference between the three groups in terms of age, gender, initial heart rate and baseline blood pressure (BP). The MAP and bleeding score (P=0.04 and P=0.0001) was significantly lower in the dexmedetomidine group than in the other two groups. Although the heart rate in the esmolol group was lower than the other two groups, the difference was not significant (P = 0.128). Unlike esmolol and magnesium sulfate groups, GOS did not decrease in the dexmedetomidine group. Conclusion: Comparison of the three groups in controlled hypotension in craniotomy surgery showed that the MAP and bleeding score of dexmedetomidine group was significantly lower than the other two groups, and the GOS didn’t decrease in this group. In general, dexmedetomidine would be a better choice for controlled hypotension in craniotomy.

scholarly journals The captopril and eprosartan influence on hemodynamic parameters in rats with renovascular hypertension

2007 ◽  
Vol 13 (4) ◽  
pp. 242-245
Author(s):  
K. E. Gavrikov ◽  
N. S. Rubanova ◽  
R. S. Chrustaleva ◽  
V. A. Tsyrlin
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Renovascular Hypertension ◽  
Arterial Blood Pressure ◽  
Baroreceptor Reflex ◽  
Hemodynamic Parameters ◽  
Hypertensive Rats ◽  
Arterial Blood ◽  
Vasorenal Hypertension

The aim of this investigation is the comparison of captopril and eprosartane influence on the level blood pressure, its variability and baroreceptor reflex in normal rats and rats with vasorenal hypertension. It was shown that hypertensive rats had higher level of blood pressure, heart rate and its variability than normotensive rats. There was no relationship between arterial blood pressure and its variability in normal as well as hypertensive rats. Captopril decreased blood pressure and had no effect on variability of blood pressure. In rats with renovascular hypertension an increased baroreflex and decreased variability of heart rate was note. Eprosartan, as well as captopril, decreased blood pressure, but increased variability of blood pressure in rats with hypertension.

A Modified Method of Quantifying the Carotid Baroreceptor-Heart Rate Reflex in Man: The Effect of Age and Blood Pressure

1989 ◽  
Vol 77 (2) ◽  
pp. 223-228 ◽  
Author(s):  
M. R. Cowie ◽  
J. M. Rawles
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Baroreflex Sensitivity ◽  
Rate Sensitivity ◽  
Modified Method ◽  
Carotid Baroreceptor ◽  
Blood Pressures ◽  
The Mean ◽  
Neck Chamber ◽  
Effect Of Age

1. Carotid baroreceptor-heart rate sensitivity has been measured non-invasively by a modified neck-chamber method that utilizes all cardiac intervals recorded in 6 min during 84 respiratory cycles. 2. In a replication study in 10 subjects the mean baroreflex sensitivity was 5.52 ms/mmHg and the mean (sd) difference between determinations was 0.70 (0.74) ms/mmHg. 3. Baroreflex sensitivity was measured in 48 untreated subjects of mean age 43 (range 20–71) years with blood pressures ranging from 104 to 202 mmHg (13.9 to 26.9 kPa) systolic and 52 to 120 mmHg (6.9 to 16.0 kPa) diastolic [average 142/87 mmHg (18.9/11.6 kPa)]. Both systolic and diastolic pressures correlated with age (r = 0.53, P < 0.001 and r = 0.44, P < 0.01). 4. Baroreflex sensitivity determined throughout respiration was log-normally distributed with a median value of 2.24 ms/mmHg, which declined with age (r = −0.63, P < 0.001). 5. After allowing for the effects of age, baroreflex sensitivity throughout respiration was not independently related to either systolic or diastolic blood pressure.

Lack of Effect of Isometric Handgrip Exercise on the Responses of the Carotid Sinus Baroreceptor Reflex in Man

1978 ◽  
Vol 55 (2) ◽  
pp. 189-194 ◽  
Author(s):  
J. Ludbrook ◽  
I. B. Faris ◽  
J. Iannos ◽  
G. G. Jamieson ◽  
W. J. Russell
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Carotid Sinus ◽  
Maximum Voluntary Contraction ◽  
Isometric Exercise ◽  
Baroreceptor Reflex ◽  
Transmural Pressure ◽  
Variable Pressure ◽  
Isometric Handgrip ◽  
Arterial Blood

1. The change in arterial pressure and heart rate resulting from alteration of carotid sinus transmural pressure by a median −34 mmHg and +33 mmHg by means of a variable-pressure neck chamber was tested in seven male volunteer subjects, at rest and during exertion of 35, 45 and 65% of maximum voluntary handgrip. 2. During 60 s of 35 and 45%, and during 30 s of 65%, of maximal voluntary handgrip there was virtually no alteration of the response of blood pressure to alteration in carotid sinus transmural pressure. 3. The bradycardic response to increase in carotid sinus transmural pressure was reduced at various times after the commencement of handgrip at 45 and 65% of maximum voluntary contraction. 4. It is concluded that a reduction in arterial baroreceptor reflex sensitivity does not play an important role in the initiation of the increase in arterial blood pressure and heart rate caused by isometric exercise. 5. The hypothesis is advanced that some of the cardiovascular changes in exercise may result from elevation of the central ‘set point’ for blood pressure.

Blood Pressure Variability in Man: Its Relation to High Blood Pressure, Age and Baroreflex Sensitivity

1980 ◽  
Vol 59 (s6) ◽  
pp. 401s-404s ◽  
Author(s):  
G. Mancia ◽  
A. Ferrari ◽  
L. Gregorini ◽  
G. Parati ◽  
G. Pomidossi ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Standard Deviation ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Blood Pressure Variability ◽  
Baroreflex Sensitivity ◽  
Variation Coefficient ◽  
Arterial Blood ◽  
Normotensive Subjects

1. Intra-arterial blood pressure and heart rate were recorded for 24 h in ambulant hospitalized patients of variable age who had normal blood pressure or essential hypertension. Mean 24 h values, standard deviations and variation coefficient were obtained as the averages of values separately analysed for 48 consecutive half-hour periods. 2. In older subjects standard deviation and variation coefficient for mean arterial pressure were greater than in younger subjects with similar pressure values, whereas standard deviation and variation coefficient for heart rate were smaller. 3. In hypertensive subjects standard deviation for mean arterial pressure was greater than in normotensive subjects of similar ages, but this was not the case for variation coefficient, which was slightly smaller in the former than in the latter group. Normotensive and hypertensive subjects showed no difference in standard deviation and variation coefficient for heart rate. 4. In both normotensive and hypertensive subjects standard deviation and even more so variation coefficient were slightly or not related to arterial baroreflex sensitivity as measured by various methods (phenylephrine, neck suction etc.). 5. It is concluded that blood pressure variability increases and heart rate variability decreases with age, but that changes in variability are not so obvious in hypertension. Also, differences in variability among subjects are only marginally explained by differences in baroreflex function.

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