Vagal cardiac function and arterial blood pressure stability

2001 ◽  
Vol 281 (5) ◽  
pp. H1870-H1880 ◽  
Author(s):  
D. Walter Wray ◽  
Kevin J. Formes ◽  
Martin S. Weiss ◽  
Albert H. O-Yurvati ◽  
Peter B. Raven ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Cardiac Function ◽  
Arterial Blood Pressure ◽  
Lower Body Negative Pressure ◽  
Low Frequency ◽  
Antimuscarinic Agents ◽  
Cuff Deflation ◽  
Arterial Blood ◽  
Before And After ◽  
The Difference

This study was designed to investigate the importance of vagal cardiac modulation in arterial blood pressure (ABP) stability before and after glycopyrrolate or atropine treatment. Changes in R-R interval (RRI) and ABP were assessed in 10 healthy young (age, 22 ± 1.8 yr) volunteers during graded lower body negative pressure (LBNP) before and after muscarinic cholinergic (MC) blockade. Transient hypertension was induced by phenylephrine (1 μg/kg body wt), whereas systemic hypotension was induced by bilateral thigh cuff deflation after a 3-min suprasystolic occlusion. Power spectral densities of systolic [systolic blood pressure (SBP)] and diastolic ABP variability were examined. Both antimuscarinic agents elicited tachycardia similarly without significantly affecting baseline ABP. The increase in SBP after phenylephrine injection (+14 ± 2 mmHg) was significantly augmented with atropine (+26 ± 2 mmHg) or glycopyrrolate (+27 ± 3 mmHg) and associated with a diminished reflex bradycardia. The decrease in SBP after cuff deflation (−9.2 ± 1.2 mmHg) was significantly greater after atropine (−15 ± 1 mmHg) or glycopyrrolate (−14 ± 1 mmHg), with abolished reflex tachycardia. LBNP significantly decreased both SBP and RRI. However, after antimuscarinic agents, the reduction in SBP was greater ( P < 0.05) and was associated with less tachycardia. Antimuscarinic agents reduced ( P < 0.05) the low-frequency (LF; 0.04–0.12 Hz) power of ABP variability at rest. The LF SBP oscillation was significantly augmented during LBNP, which was accentuated ( P < 0.05) after antimuscarinic agents and was correlated ( r = −0.79) with the decrease in SBP. We conclude that antimuscarinic agents compromised ABP stability by diminishing baroreflex sensitivity, reflecting the importance of vagal cardiac function in hemodynamic homeostasis. The difference between atropine and glycopyrrolate was not significant.

Responses of aortic chemoreceptors before and after pneumothorax in the cat

1981 ◽  
Vol 51 (3) ◽  
pp. 665-670 ◽  
Author(s):  
M. Pokorski ◽  
A. Mokashi ◽  
E. Mulligan ◽  
T. Nishino ◽  
S. Lahiri
Keyword(s):  
Blood Pressure ◽  
Arterial Blood Pressure ◽  
Experimental Manipulation ◽  
Stimulus Level ◽  
Response Curves ◽  
Co2 Response ◽  
Carotid Chemoreceptors ◽  
Arterial Blood ◽  
Before And After ◽  
The Difference

That the response of aortic chemoreceptors to hypercapnia is considerably smaller than that of carotid chemoreceptors is well accepted, but the mechanism for the difference is not known. It has been suggested that surgical exposure of the carotid body may contribute to the difference. Accordingly, the response of aortic body chemoreceptors to CO2 would be expected to resemble quantitatively that of carotid chemoreceptors after exposure of the aortic bodies by pneumothorax. The effect of opening the chest on aortic and carotid chemoreceptor responses to several levels of arterial CO2 and O2 tension and arterial blood pressure were studied in anesthetized cats. The activity of aortic chemoreceptors increased in spite of a decreased stimulus level in the thoracic cavity after pneumothorax. The activity remained higher than the control at all levels of arterial CO2 and O2 tension and arterial blood pressure. However, the slopes of CO2 response curves, which were initially small, did not change after pneumothorax. Thus a change in the normal environment of the aortic bodies by experimental manipulation did not cause the aortic chemoreceptor responses to resemble those of carotid chemoreceptors.

scholarly journals Studying Changes of the Effective Radius in Blood Vessels after Exposure of Low Extremities to Periodical Mechanical Vibrations

2019 ◽  
Author(s):  
V Nahirniak ◽  
N Kusniak ◽  
I Kashperuk-Karpiuk ◽  
L Andrushchak ◽  
T Protsak ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Blood Vessels ◽  
Arterial Blood Pressure ◽  
Vascular System ◽  
Low Frequency ◽  
Effective Radius ◽  
Mechanical Vibrations ◽  
Arterial Blood ◽  
Before And After ◽  
Blood Pressures

Background: Previous studies demonstrated a health improving effect in patients underwent an automatic vibratory massage taking 10 minutes. One of reasons that may explain a healing effect of the automatic massage is a stimulated increase in both blood circulation through vascular system and effective size of blood vessels.Objective: This paper aims to quantify a contribution of the automatic mechanical massage of low extremities into the observed reduction in arterial blood pressure and explain this effect.Material and Methods: In this study, the low extremities of male and female patients were exposed to low frequency (12 Hz) mechanical vibrations for 10 minutes and the change in systolic and diastolic arterial blood pressures before and after this procedure was measured.Results: The experiments showed there is a reduction in systolic and diastolic arterial blood pressures after vibrational massage. There were corresponding 3.5±1.8 mmHg and 3.1±1.6 mm Hg arterial blood pressure reductions among men and 5.5±3.2 mm Hg and 2.2±1.2 mm Hg reductions among women.Conclusion: We explained this effect by increasing effective radius of blood vessels. Based on the Hagen-Poiseuille equation, we made estimates for the relative change in the effective radius of blood vessels. They gave the 0.7% and 1.3% increases in the effective radius of blood vessels in low extremities in men during systole and diastole, respectively, and the corresponding 1.1% and 0.6% increases in the effective radius of blood vessels of low extremities in women during the same periods.

scholarly journals Effects of heat stress on dynamic cerebral autoregulation during large fluctuations in arterial blood pressure

2009 ◽  
Vol 107 (6) ◽  
pp. 1722-1729 ◽  
Author(s):  
R. Matthew Brothers ◽  
Rong Zhang ◽  
Jonathan E. Wingo ◽  
Kimberly A. Hubing ◽  
Craig G. Crandall
Keyword(s):  
Blood Pressure ◽  
Heat Stress ◽  
Arterial Blood Pressure ◽  
Cerebral Autoregulation ◽  
Lower Body Negative Pressure ◽  
Low Frequency ◽  
Thermal Conditions ◽  
Very Low Frequency ◽  
Arterial Blood ◽  
Dynamic Cerebral Autoregulation

Impaired cerebral autoregulation during marked reductions in arterial blood pressure may contribute to heat stress-induced orthostatic intolerance. This study tested the hypothesis that passive heat stress attenuates dynamic cerebral autoregulation during pronounced swings in arterial blood pressure. Mean arterial blood pressure (MAP) and middle cerebral artery blood velocity were continuously recorded for ∼6 min during normothermia and heat stress (core body temperature = 36.9 ± 0.1°C and 38.0 ± 0.1°C, respectively, P < 0.001) in nine healthy individuals. Swings in MAP were induced by 70-mmHg oscillatory lower body negative pressure (OLBNP) during normothermia and at a sufficient lower body negative pressure to cause similar swings in MAP during heat stress. OLBNP was applied at a very low frequency (∼0.03 Hz, i.e., 15 s on-15 s off) and a low frequency (∼0.1 Hz, i.e., 5 s on-5 s off). For each thermal condition, transfer gain, phase, and coherence function were calculated at both frequencies of OLBNP. During very low-frequency OLBNP, transfer function gain was reduced by heat stress (0.55 ± 0.20 and 0.31 ± 0.07 cm·s−1·mmHg−1 during normothermia and heat stress, respectively, P = 0.02), which is reflective of improved cerebrovascular autoregulation. During low-frequency OLBNP, transfer function gain was similar between thermal conditions (1.19 ± 0.53 and 1.01 ± 0.20 cm·s−1·mmHg−1 during normothermia and heat stress, respectively, P = 0.32). Estimates of phase and coherence were similar between thermal conditions at both frequencies of OLBNP. Contrary to our hypothesis, dynamic cerebral autoregulation during large swings in arterial blood pressure during very low-frequency (i.e., 0.03 Hz) OLBNP is improved during heat stress, but it is unchanged during low-frequency (i.e., 0.1 Hz) OLBNP.

Comparative study on effect of neutral spinal bath and neutral spinal spray on blood pressure, heart rate and heart rate variability in healthy volunteers

2018 ◽  
Vol 16 (2) ◽  
Author(s):  
Arundhati Goley ◽  
A. Mooventhan ◽  
NK. Manjunath
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Healthy Volunteers ◽  
Group Analysis ◽  
Low Frequency ◽  
Single Session ◽  
Arterial Blood ◽  
Before And After ◽  
Instantaneous Heart Rate

Abstract Background Hydrotherapeutic applications to the head and spine have shown to improve cardiovascular and autonomic functions. There is lack of study reporting the effect of either neutral spinal bath (NSB) or neutral spinal spray (NSS). Hence, the present study was conducted to evaluate and compare the effects of both NSB and NSS in healthy volunteers. Methods Thirty healthy subjects were recruited and randomized into either neutral spinal bath group (NSBG) or neutral spinal spray group (NSSG). A single session of NSB, NSS was given for 15 min to the NSBG and NSSG, respectively. Assessments were taken before and after the interventions. Results Results of this study showed a significant reduction in low-frequency (LF) to high-frequency (HF) (LF/HF) ratio of heart rate variability (HRV) spectrum in NSBG compared with NSSG (p=0.026). Within-group analysis of both NSBG and NSSG showed a significant increase in the mean of the intervals between adjacent QRS complexes or the instantaneous heart rate (HR) (RRI) (p=0.002; p=0.009, respectively), along with a significant reduction in HR (p=0.002; p=0.004, respectively). But, a significant reduction in systolic blood pressure (SBP) (p=0.037) and pulse pressure (PP) (p=0.017) was observed in NSSG, while a significant reduction in diastolic blood pressure (DBP) (p=0.008), mean arterial blood pressure (MAP) (p=0.008) and LF/HF ratio (p=0.041) was observed in NSBG. Conclusion Results of the study suggest that 15 min of both NSB and NSS might be effective in reducing HR and improving HRV. However, NSS is particularly effective in reducing SBP and PP, while NSB is particularly effective in reducing DBP and MAP along with improving sympathovagal balance in healthy volunteers.

The Study of Dynamic Response to Acute Hemorrhage by Pulse Spectrum Analysis

2006 ◽  
Vol 34 (03) ◽  
pp. 449-460 ◽  
Author(s):  
Yu Hsin Chang ◽  
Chia I Tsai ◽  
Jaung Geng Lin ◽  
Yue Der Lin ◽  
Tsai Chung Li ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Steady State ◽  
Arterial Blood Pressure ◽  
Mean Arterial Blood Pressure ◽  
Spectrum Analysis ◽  
Pulse Spectrum ◽  
Acute Hemorrhage ◽  
Arterial Blood ◽  
Percentage Difference ◽  
Before And After

Traditional Chinese Medicine (TCM) holds that Blood and Qi are fundamental substances in the human body for sustaining normal vital activity. The theory of Qi, Blood and Zang-Fu contribute the most important theoretical basis of human physiology in TCM. An animal model using conscious rats was employed in this study to further comprehend how organisms survive during acute hemorrhage by maintaining the functionalities of Qi and Blood through dynamically regulating visceral physiological conditions. Pulse waves of arterial blood pressure before and after the hemorrhage were taken in parallel to pulse spectrum analysis. Percentage differences of mean arterial blood pressure and harmonics were recorded in subsequent 5-minute intervals following the hemorrhage. Data were analyzed using a one-way analysis of variance (ANOVA) with Duncan's test for pairwise comparisons. Results showed that, within 30 minutes following the onset of acute hemorrhage,the reduction of mean arterial blood pressure was improved from 62% to 20%. Throughout the process, changes to the pulse spectrum appeared to result in a new balance over time. The percentage differences of the second and third harmonics, which were related to kidney and spleen, both increased significantly than baseline and towards another steady state. Apart from the steady state resulting from the previous stage, the percentage difference of the 4th harmonic decreased significantly to another steady state. The observed change could be attributed to the induction of functional Qi, and is a result of Qi-Blood balancing activity that organisms hold to survive against acute bleeding.

Abstract 1785: Renal Artery Angioplasty Improves Diastolic Cardiac Function In Patients With heart failure Possessing Renal Artery Stenosis.

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Eisei Yamamoto ◽  
Hitoshi Takano ◽  
Hiroyuki Tajima ◽  
Jun Tanabe ◽  
Hidekazu Kawanaka ◽  
...  
Keyword(s):  
Heart Failure ◽  
Blood Pressure ◽  
Blood Flow ◽  
Cardiac Function ◽  
Renal Artery ◽  
Renal Blood Flow ◽  
Renal Artery Stenosis ◽  
Arterial Blood Pressure ◽  
Arterial Blood ◽  
Diastolic Cardiac Function

Background: Renal artery stenosis (RAS) often plays an important role not only in malignant hypertension but also in sudden development of heart failure (HF) so called ‘flash pulmonary edema’ or chronic HF refractory to medical treatment. One of the possible mechanisms whereby RAS affects these unique conditions of HF is suppression of LV compliance through the complex interaction between neurohormonal systems originating from the reduction of renal blood flow. Renal artery angioplasty is expected to be an effective treatment for restoring renal blood flow in patients with RAS. The aim of the present study was whether the angioplasty can improve the impaired neurohormonal systems and diastolic cardiac function in patients with RAS. Methods: A prospective analysis was performed in 18 HF patients with RAS (age: 72±6, 3 females, NYHA I/II/III: 5/9/4) who underwent renal artery angioplasty between 2005 and 2007. Four patients with significant bilateral RAS and 3 patients with unilateral RAS in the vessel supplying a functional solitary kidney were included. We monitored the changes of biochemical and neurohormonal markers and blood pressure. Cardiac function was evaluated by tissue Doppler echocardiogram before and 3 months after the procedure. Results: Technical success was achieved in all interventions. The results are shown in table . Systolic arterial blood pressure significantly decreased by renal angioplasty. B-type natriuretic peptide (BNP) was significantly reduced 3 months after the angioplasty, whereas the change of sCr or angiotensinII was not statistically significant. Myocardial early diastolic velocity (Em), a parameter of diastolic LV function, was significantly improved compared with that measured before the procedure. Conclusions: In patients with either overt or latent HF possessing RAS, renal artery angioplasty not only decreases arterial blood pressure but also improves diastolic cardiac function in parallel with the reduction of BNP level.

scholarly journals Interrelationships between pulse arrival time and arterial blood pressure during postural transitions before and after spaceflight

2019 ◽  
Vol 127 (4) ◽  
pp. 1050-1057
Author(s):  
Katelyn N. Wood ◽  
Danielle K. Greaves ◽  
Richard L. Hughson
Keyword(s):  
Blood Pressure ◽  
Arterial Blood Pressure ◽  
Arrival Time ◽  
Standing Posture ◽  
Pulse Arrival Time ◽  
Arterial Blood ◽  
Increased Risk ◽  
Before And After ◽  
Acute Changes ◽  
Pulse Arrival

We tested the hypothesis that acute changes in arterial blood pressure (BP) when astronauts moved between supine and standing posture before and after spaceflight can be tracked by beat-to-beat changes in pulse arrival time (PAT). Nine male crewmembers (45 ± 7 yr of age; mean mission length: 165 ± 13 days) participated in a standardized supine-to-sit-to-stand test (5 min-30 s-3 min) before flight and 1 day following return to Earth with continuous monitoring of ECG and finger arterial BP. PAT was determined from the R-wave of the ECG to the foot of the BP waveform. On average, modest cardiovascular deconditioning was detected by ~10 beats/min increase in heart rate in supine and standing posture after spaceflight ( P < 0.05). When looking across the full data collection period, the r2 values between inverse of PAT (1/PAT) and systolic (SBP) and diastolic BP (DBP) varied considerably between individuals (SBP preflight 0.142 ± 0.186, postflight 0.262 ± 0.243). Individual variability was consistent during periods of transition (SBP preflight 0.284 ± 0.324, postflight 0.297 ± 0.269); however, when SBP dropped >20 mmHg, r2 was significant in 5 of 5 preflight tests and 5 of 7 postflight tests. The standard error of the estimate based on a simple linear model during both pre- and postflight testing was 9–11 mmHg for SBP and 6–7 mmHg for DBP. Overall, the results support the hypothesis that PAT tracked dynamic changes in BP. PAT as a noninvasive, nonintrusive surrogate for changes in BP could be developed as an indicator of risk for syncope on return from spaceflight or other Earth-based applications. NEW & NOTEWORTHY Astronauts returning to Earth’s gravity are at increased risk of low blood pressure on standing. Arterial pulse arrival time tracked the decrease in arterial blood pressure on moving from supine to upright posture. Nonintrusive technology providing indicators sensitive to acute changes in blood pressure could act as an early warning system to identify risk for hypotension that place astronauts, or people on Earth, at risk of impaired cognitive performance, fainting, and falls.

Cardiopulmonary reflexes and blood pressure in exercising sinoaortic-denervated dogs

1984 ◽  
Vol 57 (5) ◽  
pp. 1417-1421 ◽  
Author(s):  
D. A. Daskalopoulos ◽  
J. T. Shepherd ◽  
S. C. Walgenbach
Keyword(s):  
Blood Pressure ◽  
Arterial Blood Pressure ◽  
Vagal Afferents ◽  
Systemic Resistance ◽  
Vigorous Exercise ◽  
Arterial Blood ◽  
Resistance Vessels ◽  
Before And After ◽  
Cervical Vagotomy ◽  
Cardiopulmonary Receptors

To examine the role of cardiopulmonary receptors in arterial blood pressure regulation during and after exercise, conscious dogs with chronic sinoaortic denervation were subjected to 12 min of light exercise and 12 min of exercise that increased in severity every 3 min. Hemodynamic measurements were made before and after interruption of cardiopulmonary afferents by bilateral cervical vagotomy. During both exercise protocols, after an initial transient decrease, the arterial blood pressure remained close to resting values before and after vagotomy. On cessation of the graded exercise, the arterial blood pressure did not change before, but a rapid and sustained increase in pressure occurred after vagotomy. At the time of this increase the cardiac output and heart rate were returning rapidly to the resting level. The study demonstrates that in the chronic absence of arterial baroreflexes, vagal afferents prevent a rise in arterial blood pressure after vigorous exercise presumably by the action of cardiopulmonary receptors causing a rapid dilatation of systemic resistance vessels.

scholarly journals Cerebral Blood Flow Changes during Cortical Spreading Depression are Not Altered by Inhibition of Nitric Oxide Synthesis

1994 ◽  
Vol 14 (6) ◽  
pp. 939-943 ◽  
Author(s):  
Zheng Gang Zhang ◽  
Michael Chopp ◽  
Kenneth I. Maynard ◽  
Michael A. Moskowitz
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Arterial Blood Pressure ◽  
Cortical Spreading Depression ◽  
Spreading Depression ◽  
Arterial Blood ◽  
Nos Inhibitors ◽  
Before And After ◽  
Male Wistar Rats

CBF increases concomitantly with cortical spreading depression (CSD). We tested the hypothesis that CBF changes during CSD are mediated by nitric oxide (NO). Male Wistar rats (n = 23) were subjected to KCl-induced CSD before and after administration of nitric oxide synthase (NOS) inhibitors N-nitro-l-arginine (L-NNA) or N-nitro-l-arginine methyl ester (L-NAME) and in nontreated animals. CBF, CSD, and mean arterial blood pressure were recorded. Brain NOS activity was measured in vitro in control, L-NNA, and L-NAME-treated rats by the conversion of [3H]arginine to [3H]citrulline. Our data show that the NOS inhibitors did not significantly change regional CBF (rCBF) during CSD, even though cortical NOS activity was profoundly depressed and systemic arterial blood pressure was significantly increased. Our data suggest that rCBF during CSD in rats is not regulated by NO.

Ouabain prevents loss of autoregulation in rat pial arterioles caused by reoxygenation after a brief hypoxic episode

1989 ◽  
Vol 67 (5) ◽  
pp. 423-427 ◽  
Author(s):  
J. Kettler ◽  
B. Y. Ong ◽  
D. Bose
Keyword(s):  
Blood Pressure ◽  
Arterial Blood Pressure ◽  
Protective Effects ◽  
Cranial Window ◽  
Arterial Blood ◽  
Hypoxic Episode ◽  
Electrogenic Sodium Pump ◽  
Before And After ◽  
Pressure Changes ◽  
Arteriolar Diameter

Pial arteriolar diameter changes inversely with changes in systemic arterial blood pressure. Such changes are consistent with autoregulatory functions. These responses are reduced by a brief period of hypoxia followed by reoxygenation. By using an open cranial window preparation we assessed the changes in pial arteriolar diameters during blood pressure changes in rats induced by hemorrhage and reinfusion of blood, before and after a brief period of hypoxia. The slopes of the changes in pial arteriolar diameter as a function of mean arterial blood pressure were −0.47 ± 0.26 μm/mmHg (mean ± SD; 1 mmHg = 133.3 Pa) before hypoxia and −0.11 ± 0.23 μm/mmHg after hypoxia in the untreated rats. In ouabain-treated rats, corresponding slopes were −0.42 ± 0.24 and −0.46 ± 0.22 μm/mmHg. The observed protective effects of ouabain might be a blockade of the Na–K pump in the sarcolemma of the vascular smooth muscle.Key words: vascular smooth muscle, electrogenic sodium pump, metabolic inhibition.

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