Time-Course of the Reduction of Baroreceptor Sensitivity in Experimental Hypertensive Rabbits

1976 ◽  
Vol 51 (s3) ◽  
pp. 369s-372s ◽  
Author(s):  
Jennifer E. Angell-James ◽  
M. J. George
Keyword(s):  
Blood Pressure ◽  
Aortic Arch ◽  
Time Course ◽  
Baroreflex Sensitivity ◽  
Intact Animal ◽  
Baroreceptor Sensitivity ◽  
Hypertensive Group ◽  
Medial Sclerosis

1. Hypertension was produced experimentally in three groups of rabbits by atherosclerosis, medial sclerosis and renal encapsulation. 2. The sensitivity of afferent baroreceptor fibre recordings, obtained from an isolated perfused aortic arch preparation, was reduced in all three treated groups. 3. The reduction of baroreceptor sensitivity was directly related to the increase in the lability of the blood pressure in the intact animal and to the reduction of the distensibility of the perfused region. 4. There was a closer relationship between the length of time the rabbits had been hypertensive and the reduction in the baroreceptor sensitivity, than to the level of their blood pressure. 5. The reduction of baroreflex sensitivity obtained by the infusion of phenylephrine was also directly correlated with the period of the hypertension. 6. Baroreceptor resetting occurred to a higher pressure in the renal hypertensive group.

Exercise blood pressure and baroreflex function in borderline hypertensive and normotensive young men

1985 ◽  
Vol 68 (6) ◽  
pp. 631-638 ◽  
Author(s):  
Kevin Welsh ◽  
Ann Ward ◽  
Peter Hanson
Keyword(s):  
Blood Pressure ◽  
Systolic Blood Pressure ◽  
Baroreflex Sensitivity ◽  
Treadmill Exercise ◽  
Handgrip Exercise ◽  
Isometric Handgrip ◽  
Borderline Hypertension ◽  
Hypertensive Group ◽  
Isometric Handgrip Exercise ◽  
Rest And Exercise

1. Resting carotid baroreflex sensitivity and blood pressure responses to standardized conditions of rest and exercise were measured in 17 borderline hypertensive males and 12 normotensive males. 2. The borderline hypertensive group had significantly higher systolic and diastolic blood pressures during orthostatic rest and isometric handgrip exercise and higher systolic blood pressure during supine rest and submaximum and maximum treadmill exercise. 3. The borderline hypertensive group had an attenuation of baroreflex sensitivity compared with the normotensive group. Resting baroreflex sensitivity was significantly correlated with absolute systolic blood pressure during supine rest, orthostatic rest, isometric handgrip exercise and submaximum treadmill exercise. 4. The results indicate that blood pressure is regulated at a significantly higher level during rest and exercise in borderline hypertension and is associated with reduced baroreflex sensitivity measured at supine rest.

Time course analysis of baroreflex sensitivity during postural stress

2006 ◽  
Vol 291 (6) ◽  
pp. H2864-H2874 ◽  
Author(s):  
Berend E. Westerhof ◽  
Janneke Gisolf ◽  
John M. Karemaker ◽  
Karel H. Wesseling ◽  
Niels H. Secher ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Time Domain ◽  
Time Course ◽  
Baroreflex Sensitivity ◽  
Frequency Domain Analysis ◽  
Vagal Activity ◽  
Free Standing ◽  
Postural Stress ◽  
Before And After ◽  
Tight Correlation

Postural stress requires immediate autonomic nervous action to maintain blood pressure. We determined time-domain cardiac baroreflex sensitivity (BRS) and time delay (τ) between systolic blood pressure and interbeat interval variations during stepwise changes in the angle of vertical body axis (α). The assumption was that with increasing postural stress, BRS becomes attenuated, accompanied by a shift in τ toward higher values. In 10 healthy young volunteers, α included 20 degrees head-down tilt (−20°), supine (0°), 30 and 70 degrees head-up tilt (30°, 70°), and free standing (90°). Noninvasive blood pressures were analyzed over 6-min periods before and after each change in α. The BRS was determined by frequency-domain analysis and with xBRS, a cross-correlation time-domain method. On average, between 28 (−20°) to 45 (90°) xBRS estimates per minute became available. Following a change in α, xBRS reached a different mean level in the first minute in 78% of the cases and in 93% after 6 min. With increasing α, BRS decreased: BRS = −10.1·sin(α) + 18.7 ( r2 = 0.99) with tight correlation between xBRS and cross-spectral gain ( r2 ∼ 0.97). Delay τ shifted toward higher values. In conclusion, in healthy subjects the sensitivity of the cardiac baroreflex obtained from time domain decreases linearly with sin(α), and the start of baroreflex adaptation to a physiological perturbation like postural stress occurs rapidly. The decreases of BRS and reduction of short τ may be the result of reduced vagal activity with increasing α.

Patterns of Cerebral Blood Flow and Systemic Hemodynamics During Arithmetic Processing

2008 ◽  
Vol 22 (2) ◽  
pp. 81-90 ◽  
Author(s):  
Natalie Werner ◽  
Neval Kapan ◽  
Gustavo A. Reyes del Paso
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Time Course ◽  
Doppler Sonography ◽  
Transcranial Doppler Sonography ◽  
Systemic Hemodynamics ◽  
Heart Period ◽  
Blood Flow Velocities ◽  
Flow Velocities

The present study explored modulations in cerebral blood flow and systemic hemodynamics during the execution of a mental calculation task in 41 healthy subjects. Time course and lateralization of blood flow velocities in the medial cerebral arteries of both hemispheres were assessed using functional transcranial Doppler sonography. Indices of systemic hemodynamics were obtained using continuous blood pressure recordings. Doppler sonography revealed a biphasic left dominant rise in cerebral blood flow velocities during task execution. Systemic blood pressure increased, whereas heart period, heart period variability, and baroreflex sensitivity declined. Blood pressure and heart period proved predictive of the magnitude of the cerebral blood flow response, particularly of its initial component. Various physiological mechanisms may be assumed to be involved in cardiovascular adjustment to cognitive demands. While specific contributions of the sympathetic and parasympathetic systems may account for the observed pattern of systemic hemodynamics, flow metabolism coupling, fast neurogenic vasodilation, and cerebral autoregulation may be involved in mediating cerebral blood flow modulations. Furthermore, during conditions of high cardiovascular reactivity, systemic hemodynamic changes exert a marked influence on cerebral blood perfusion.

Time course study of blood pressure in children over a three-year period. Bogalusa Heart Study

Hypertension ◽  
1980 ◽  
Vol 2 (4) ◽  
pp. 102-108 ◽  
Author(s):  
A. W. Voors ◽  
L. S. Webber ◽  
G. S. Berenson
Keyword(s):  
Blood Pressure ◽  
Time Course ◽  
Bogalusa Heart Study ◽  
Heart Study ◽  
Time Course Study

Exercise and pyridostigmine prevents gastric emptying delay and increase blood pressure and cisplatin-induced baroreflex sensitivity in rats

Life Sciences ◽  
2021 ◽  
Vol 267 ◽  
pp. 118972
Author(s):  
Mariana Sousa Silva ◽  
Yasmim de Andrade Gomes ◽  
Mickael Laudrup de Sousa Cavalcante ◽  
Pedro Victor Nogueira Telles ◽  
Alda Cássia Alves da Silva ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Gastric Emptying ◽  
Baroreflex Sensitivity ◽  
Increase Blood Pressure

Heart rate and blood pressure variability and baroreflex sensitivity in patients with acute brain injury

2005 ◽  
Vol 20 (4) ◽  
pp. 394 ◽  
Author(s):  
V. Papaioannou ◽  
M. Giannakou ◽  
N. Maglaveras ◽  
E. Sofianos ◽  
M. Giala
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Brain Injury ◽  
Blood Pressure Variability ◽  
Baroreflex Sensitivity ◽  
Acute Brain Injury

Time course of insulin resistance associated with feeding dogs a high-fat diet

1997 ◽  
Vol 272 (1) ◽  
pp. E147-E154 ◽  
Author(s):  
A. P. Rocchini ◽  
P. Marker ◽  
T. Cervenka
Keyword(s):  
Insulin Resistance ◽  
Blood Pressure ◽  
Glucose Uptake ◽  
Dose Response ◽  
High Fat Diet ◽  
Time Course ◽  
Rapid Development ◽  
Diet Group ◽  
Whole Body ◽  
High Fat

The current study evaluated both the time course of insulin resistance associated with feeding dogs a high-fat diet and the relationship between the development of insulin resistance and the increase in blood pressure that also occurs. Twelve adult mongrel dogs were chronically instrumented and randomly assigned to either a control diet group (n = 4) or a high-fat diet group (n = 8). Insulin resistance was assessed by a weekly, single-dose (2 mU.kg-1.min-1) euglycemic-hyperinsulinemic clamp on all dogs. Feeding dogs a high-fat diet was associated with a 3.7 +/- 0.5 kg increase in body weight, a 20 +/- 4 mmHg increase in mean blood pressure, a reduction in insulin-mediated glucose uptake [(in mumol-kg-1.min-1) decreasing from 72 +/- 6 before to 49 +/- 7 at 1 wk, 29 +/- 3 at 3 wk, and 30 +/- 2 at 6 wk of the high-fat diet, P < 0.01]. and a reduced insulin-mediated increase in cardiac output. In eight dogs (4 high fat and 4 control), the dose-response relationship of insulin-induced glucose uptake also was studied. The whole body glucose uptake dose-response curve was shifted to the right, and the rate of maximal whole body glucose uptake was significantly decreased (P < 0.001). Finally, we observed a direct relationship between the high-fat diet-induced weekly increase in mean arterial pressure and the degree to which insulin resistance developed. In summary, the current study documents that feeding dogs a high-fat diet causes the rapid development of insulin resistance that is the result of both a reduced sensitivity and a reduced responsiveness to insulin.

Comparison of the Effect-site keOs of Propofol for Blood Pressure and EEG Bispectral Index in Elderly and Younger Patients

1999 ◽  
Vol 90 (6) ◽  
pp. 1517-1527. ◽  
Author(s):  
Tomiei Kazama ◽  
Kazuyuki Ikeda ◽  
Koji Morita ◽  
Mutsuhito Kikura ◽  
Matsuyuki Doi ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Plasma Concentration ◽  
Bispectral Index ◽  
Time Course ◽  
Drug Infusion ◽  
Time Data ◽  
Aged Patients ◽  
Younger Patients ◽  
Spectral Edge Frequency ◽  
Effect Site

Background Drug effect lags behind the blood concentration. The goal of this investigation was to determine the time course of plasma concentration and the effects of propofol demonstrated by electroencephalogram or blood pressure changes and to compare them between elderly and young or middle-aged patients. Methods A target-controlled infusion was used to rapidly attain and maintain four sequentially increasing, randomly selected plasma propofol concentrations from 1 to 12 microg/ml in 41 patients aged 20-85 yr. The target concentration was maintained for about 30 min. Bispectral index (BIS), spectral edge frequency, and systolic blood pressure (SBP) were used as measures of propofol effect. Because the time courses of these measures following the started drug infusion showed an exponential pattern, the first-order rate constant for equilibration of the effect site with the plasma concentration (k(eO)) was estimated by fitting a monoexponential model to the effect versus time data resulting from the pseudo-steady-state propofol plasma concentration profile. Results The half-times for the plasma-effect-site equilibration for BIS were 2.31, 2.30, 2.29, and 2.37 min in patients aged 20-39, 40-59, 60-69, and 70-85 yr, respectively (n = 10 or 11 each). The half-times for SBP were 5.68, 5.92, 8.87, and 10.22 min in the respective age groups. All were significantly longer than for BIS (P &lt; 0.05). The propofol concentration at half of the maximal decrease of SBP was significantly greater (P &lt; 0.05) in the elderly than in the younger patients. Conclusions The effect of propofol on BIS occurs more rapidly than its effect on SBP. Age has no effect on the rate of BIS reduction with increasing propofol concentration, whereas with increasing age, SBP decreases to a greater degree but more slowly.

scholarly journals Blood pressure reduction after gastric bypass surgery is explained by a decrease in cardiac output

2017 ◽  
Vol 122 (2) ◽  
pp. 223-229 ◽  
Author(s):  
Peter M. van Brussel ◽  
Bas van den Bogaard ◽  
Barbara A. de Weijer ◽  
Jasper Truijen ◽  
C.T. Paul Krediet ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Gastric Bypass ◽  
Body Weight ◽  
Cardiac Output ◽  
Baroreflex Sensitivity ◽  
Bypass Surgery ◽  
Gastric Bypass Surgery ◽  
Left Ventricular ◽  
Ventricular Contractility ◽  
Left Ventricular Contractility

Blood pressure (BP) decreases in the first weeks after Roux-and-Y gastric bypass surgery. Yet the pathophysiology of the BP-lowering effects observed after gastric bypass surgery is incompletely understood. We evaluated BP, systemic hemodynamics, and baroreflex sensitivity in 15 obese women[mean age 42 ± 7 standard deviation (SD) yr, body mass index 45 ± 6 kg/m2] 2 wk before and 6 wk following Roux-and-Y gastric bypass surgery. Six weeks after gastric bypass surgery, mean body weight decreased by 13 ± 5 kg (10%, P < 0.001). Office BP decreased from 137 ± 10/86 ± 6 to 128 ± 12/81 ± 9 mmHg ( P < 0.001, P < 0.01), while daytime ambulatory BP decreased from 128 ± 14/80 ± 9 to 114 ± 10/73 ± 6 mmHg ( P = 0.01, P = 0.05), whereas nighttime BP decreased from 111 ± 13/66 ± 7 to 102 ± 9/62 ± 7 mmHg ( P = 0.04, P < 0.01). The decrease in BP was associated with a 1.6 ± 1.2 l/min (20%, P < 0.01) decrease in cardiac output (CO), while systemic vascular resistance increased (153 ± 189 dyn·s·cm−5, 15%, P < 0.01). The maximal ascending slope in systolic blood pressure decreased (192 mmHg/s, 19%, P = 0.01), suggesting a reduction in left ventricular contractility. Baroreflex sensitivity increased from 9.0 [6.4–14.3] to 13.8 [8.5–19.0] ms/mmHg (median [interquartile range]; P < 0.01) and was inversely correlated with the reductions in heart rate ( R = −0.64, P = 0.02) and CO ( R = −0.61, P = 0.03). In contrast, changes in body weight were not correlated with changes in either BP or CO. The BP reduction following Roux-and-Y gastric bypass surgery is correlated with a decrease in CO independent of changes in body weight. The contribution of heart rate to the reduction in CO together with enhanced baroreflex sensitivity suggests a shift toward increased parasympathetic cardiovascular control. NEW & NOTEWORTHY The reason for the decrease in blood pressure (BP) in the first weeks after gastric bypass surgery remains to be elucidated. We show that the reduction in BP following surgery is caused by a decrease in cardiac output. In addition, the maximal ascending slope in systolic blood pressure decreased suggesting a reduction in left ventricular contractility and cardiac workload. These findings help to understand the physiological changes following gastric bypass surgery and are relevant in light of the increased risk of heart failure in these patients.

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