Effect of static leg muscle contraction on blood pressure and pulse interval rhythmicity and arterial baroreflex control of pulse interval in healthy volunteers

1993 ◽  
Vol 43 ◽  
pp. 113
Author(s):  
F. Weise ◽  
B. Fiser ◽  
N. Honzikova
Keyword(s):  
Blood Pressure ◽  
Muscle Contraction ◽  
Healthy Volunteers ◽  
Pulse Interval ◽  
Arterial Baroreflex ◽  
Baroreflex Control ◽  
Leg Muscle

Thyroid status influences baroreflex function and autonomic contributions to arterial pressure and heart rate

2001 ◽  
Vol 280 (5) ◽  
pp. H2061-H2068 ◽  
Author(s):  
C. Michael Foley ◽  
Richard M. McAllister ◽  
Eileen M. Hasser
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Arterial Pressure ◽  
Logistic Function ◽  
Arterial Baroreflex ◽  
Thyroid Status ◽  
Baroreflex Control ◽  
Baroreflex Function ◽  
Resting Blood Pressure ◽  
Sympathetic Influence

The effect of thyroid status on arterial baroreflex function and autonomic contributions to resting blood pressure and heart rate (HR) were evaluated in conscious rats. Rats were rendered hyperthyroid (Hyper) or hypothyroid (Hypo) with triiodothyronine and propylthiouracil treatments, respectively. Euthyroid (Eut), Hyper, and Hypo rats were chronically instrumented to measure mean arterial pressure (MAP), HR, and lumbar sympathetic nerve activity (LSNA). Baroreflex function was evaluated with the use of a logistic function that relates LSNA or HR to MAP during infusion of phenylephrine and sodium nitroprusside. Contributions of the autonomic nervous system to resting MAP and HR were assessed by blocking autonomic outflow with trimethaphan. In Hypo rats, the arterial baroreflex curve for both LSNA and HR was shifted downward. Hypo animals exhibited blunted sympathoexcitatory and tachycardic responses to decreases in MAP. Furthermore, the data suggest that in Hypo rats, the sympathetic influence on HR was predominant and the autonomic contribution to resting MAP was greater than in Eut rats. In Hyper rats, arterial baroreflex function generally was similar to that in Eut rats. The autonomic contribution to resting MAP was not different between Hyper and Eut rats, but predominant parasympathetic influence on HR was exhibited in Hyper rats. The results demonstrate baroreflex control of LSNA and HR is attenuated in Hypo but not Hyper rats. Thyroid status alters the balance of sympathetic to parasympathetic tone in the heart, and the Hypo state increases the autonomic contributions to resting blood pressure.

scholarly journals Arterial baroreflex regulation of muscle sympathetic single-unit activity in men: influence of resting blood pressure

2020 ◽  
Vol 318 (4) ◽  
pp. H937-H946 ◽  
Author(s):  
Anthony V. Incognito ◽  
Milena Samora ◽  
Andrew D. Shepherd ◽  
Roberta A. Cartafina ◽  
Gabriel M. N. Guimarães ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Single Unit ◽  
Cardiac Cycle ◽  
Single Units ◽  
Arterial Baroreflex ◽  
Baroreflex Control ◽  
Pharmacological Manipulation ◽  
Operating Range ◽  
Resting Blood Pressure ◽  
Spike Firing

The arterial baroreflex has dominant control over multiunit muscle sympathetic nerve activity (MSNA) burst occurrence, but whether this extends to all single units or is influenced by resting blood pressure status is unclear. In 22 men (32 ± 8 yr), we assessed 68 MSNA single units during sequential bolus injections of nitroprusside and phenylephrine (modified Oxford). Sympathetic baroreflex sensitivity (sBRS) was quantified as the weighted negative linear regression slope between diastolic blood pressure (DBP) and single-unit spike firing probability and multiple spike firing. Strong negative linear relationships ( r ≥ −0.50) between DBP and spike firing probability were observed in 63/68 (93%) single units (−2.27 ± 1.27%·cardiac cycle−1·mmHg−1 [operating range, 18 ± 8 mmHg]). In contrast, only 45/68 (66%) single units had strong DBP-multiple spike firing relationships (−0.13 ± 0.18 spikes·cardiac cycle−1·mmHg−1 [operating range, 14 ± 7 mmHg]). Participants with higher resting DBP (65 ± 3 vs. 77 ± 3 mmHg, P < 0.001) had similar spike firing probability sBRS (low vs. high, −2.08 ± 1.08 vs. −2.46 ± 1.42%·cardiac cycle−1·mmHg−1, P = 0.33), but a smaller sBRS operating range (20 ± 6 vs. 16 ± 9 mmHg, P = 0.01; 86 ± 24 vs. 52 ± 25% of total range, P < 0.001) and a higher proportion of single units without arterial baroreflex control outside this range [6/31 (19%) vs. 21/32 (66%), P < 0.001]. Participants with higher resting DBP also had fewer single units with arterial baroreflex control of multiple spike firing (79 vs. 53%, P = 0.04). The majority of MSNA single units demonstrate strong arterial baroreflex control over spike firing probability during pharmacological manipulation of blood pressure. Changes in single-unit sBRS operating range and control of multiple spike firing may represent altered sympathetic recruitment patterns associated with the early development of hypertension. NEW & NOTEWORTHY Muscle sympathetic single units can be differentially controlled during stress. In contrast, we demonstrate that 93% of single units maintain strong arterial baroreflex control during pharmacological manipulation of blood pressure. Interestingly, the operating range and proportion of single units that lose arterial baroreflex control outside of this range are influenced by resting blood pressure levels. Altered single unit, but not multiunit, arterial baroreflex control may represent changes in sympathetic recruitment patterns in early stage development of hypertension.

Vasopressin potentiates ventricular and arterial reflexes in the conscious nonhuman primate

1989 ◽  
Vol 256 (6) ◽  
pp. H1546-H1552 ◽  
Author(s):  
M. W. Barazanji ◽  
K. G. Cornish
Keyword(s):  
Blood Pressure ◽  
Nonhuman Primate ◽  
Nucleus Tractus Solitarius ◽  
Control Level ◽  
Cardiovascular Responses ◽  
Left Ventricular ◽  
Arterial Baroreflex ◽  
Baroreflex Control ◽  
Arterial Blood ◽  
Rule Out

The effect of arginine vasopressin (AVP) on the arterial baroreflex control of heart rate (HR) was studied in intact and sinoaortic-denervated (SAD) conscious, unrestrained monkeys. A baroreflex curve for mean arterial blood pressure (MABP) and HR was determined before and during intravenous infusion of AVP (2-4 mU.kg-1.min-1) and after the AVP vascular antagonist "Manning compound" [( d(CH2)5Tyr(Me)]AVP, 40 micrograms/kg), while AVP infusion was kept running. The sensitivity (slope) of the arterial baroreflex, as well as the reflex bradycardia induced by high blood pressure, increased significantly during AVP and returned to the control level after Manning compound. The effect of AVP on the Bezold-Jarisch reflex (induced by stimulating left ventricular receptors with 4 micrograms/kg veratridine injected in the left atrium) was also studied. The cardiovascular responses to veratridine were examined before and during AVP and after administration of Manning compound together with AVP infusion. AVP significantly potentiated the hypotension and the bradycardia produced by veratridine, whereas Manning compound blunted this potentiation. The ventricular reflex in SAD monkeys was significantly greater than in intact monkeys. We conclude that, in the conscious nonhuman primate, AVP potentiates the sensitivity of the baroreflex control of HR as well as the Bezold-Jarisch reflex. The potentiation of the Bezold-Jarisch reflex by AVP in the SAD animals is consistent with a central action, since the baroreceptors and ventricular receptors both have connections in the nucleus tractus solitarius. However, it does not rule out the possibility of peripheral actions on receptors or end organs.

Cardiovascular Response to Coughing: Its Value in the Assessment of Autonomic Nervous Control

1989 ◽  
Vol 77 (3) ◽  
pp. 305-310 ◽  
Author(s):  
E. J. Van Lieshout ◽  
J. J. Van Lieshout ◽  
A. D. J. Ten Harkel ◽  
W. Wieling
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cardiovascular Response ◽  
Arterial Hypotension ◽  
Valsalva Manoeuvre ◽  
Arterial Baroreflex ◽  
Nervous Control ◽  
Baroreflex Control ◽  
Standing Up ◽  
Forced Breathing

1. The relationship between blood pressure and heart rate responses to coughing was investigated in 10 healthy subjects in three body positions and compared with the circulatory responses to commonly used autonomic function tests: forced breathing, standing up and the Valsalva manoeuvre. 2. We observed a concomitant intra-cough increase in supine heart rate and blood pressure and a sustained post-cough elevation of heart rate in the absence of arterial hypotension. These findings indicate that the sustained increase in heart rate in response to coughing is not caused by arterial hypotension and that these heart rate changes are not under arterial baroreflex control. 3. The maximal change in heart rate in response to coughing (28 ± 8 beats/min) was comparable with the response to forced breathing (29 ± 9 beats/min, P > 0.4), with a reasonable correlation (r = 0.67, P < 0.05), and smaller than the change in response to standing up (41 ± 9 beats/min, P < 0.01) and to the Valsalva manoeuvre (39 ± 13 beats/min, P < 0.01). 4. Quantifying the initial heart rate response to coughing offers no advantage in measuring cardiac acceleratory capacity; standing up and the Valsalva manoeuvre are superior to coughing in evaluating arterial baroreflex cardiovascular function.

Effects of aging on 24-h dynamic baroreceptor control of heart rate in ambulant subjects

1995 ◽  
Vol 268 (4) ◽  
pp. H1606-H1612 ◽  
Author(s):  
G. Parati ◽  
A. Frattola ◽  
M. Di Rienzo ◽  
P. Castiglioni ◽  
A. Pedotti ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Systolic Blood Pressure ◽  
Baroreflex Sensitivity ◽  
Regression Line ◽  
Domain Analysis ◽  
Pulse Interval ◽  
Alpha Coefficient ◽  
Baroreflex Control ◽  
Effects Of Aging

The effects of aging on the dynamic modulation of baroreflex sensitivity over 24 h was assessed in eight elderly (mean age +/- SD, 63.9 +/- 3.2 yr) and in eight young (23.9 +/- 6.1 yr) mild or moderate essential hypertensive patients, who were subject to a 24-h intra-arterial (Oxford technique) blood pressure recording in ambulatory conditions. The sensitivity of baroreflex control of the heart rate was dynamically assessed by quantifying 1) the slope of the regression line between pulse interval (the reciprocal of heart rate) and systolic blood pressure changes over spontaneously occurring hypertension-bradycardia or hypotension-tachycardia sequences (time domain analysis) and 2) the ratio between spectral-powers of pulse interval and systolic blood pressure around 0.1 Hz (alpha-coefficient: frequency domain analysis). The 24-h average sequence slope was lower in old than in young individuals (4.4 +/- 0.5 vs. 9.9 +/- 1.3 and 4.8 +/- 0.7 vs. 8.4 +/- 1.4 ms/mmHg for hypertension-bradycardia and hypotension-tachycardia sequences, respectively; P < 0.05 for both). Similar results were obtained by using the alpha-coefficient approach. The marked nighttime increase in baroreflex sensitivity observed in young individuals was much less evident in the elderly. Thus 24-h baroreflex sensitivity is markedly impaired by aging. The impairment becomes manifest also as an inability to increase baroreflex sensitivity at night.

Post-Adrenalectomy Hypotension in Rats; Absence of Baroreflex Resetting or Effect of Naloxone

1983 ◽  
Vol 64 (4) ◽  
pp. 371-376 ◽  
Author(s):  
S. M. Gardiner ◽  
T. Bennett
Keyword(s):  
Blood Pressure ◽  
Arterial Blood Pressure ◽  
Tap Water ◽  
Sinus Node ◽  
Pulse Interval ◽  
Baroreflex Control ◽  
Systemic Arterial Blood Pressure ◽  
Arterial Blood ◽  
Blood Pressures ◽  
Adrenalectomized Rats

1. Male Wistar rats were either bilaterally adrenalectomized or sham-operated, and given 1% sodium chloride solution instead of tap water to drink. Seven days later, arterial blood pressures were recorded directly from conscious freely moving rats. 2. Systolic and diastolic blood pressures were significantly lower in the adrenalectomized rats, whereas heart rates were significantly higher than in sham-operated animals. The tachycardia was due to a combination of sympathetic hyperactivity and reduced vagal tone, which may have been reflex responses to a reduction in effective blood volume. 3. Baroreflex control of the sinus node was assessed from the pulse interval responses to rises (induced by methoxamine) or falls (induced by glyceryl trinitrate or sodium nitroprusside) in systemic arterial blood pressure. The relation between pulse interval and systolic blood pressure was described by the same curve in sham-operated and adrenalectomized rats, indicating that, in the latter, there was no change in baroreflex setting or sensitivity. 4. Intravenous administration of naloxone (2mg/kg) had no effect on systemic arterial blood pressure in adrenalectomized rats, suggesting that endogenous opiates were not contributing to the hypotension.

Applicability of recent methods used to estimate spontaneous baroreflex sensitivity to resting mice

2008 ◽  
Vol 294 (1) ◽  
pp. R142-R150 ◽  
Author(s):  
Dominique Laude ◽  
Véronique Baudrie ◽  
Jean-Luc Elghozi
Keyword(s):  
Baroreflex Sensitivity ◽  
Low Frequency ◽  
Pulse Interval ◽  
Arterial Baroreflex ◽  
Baroreflex Control ◽  
Spectral Estimates ◽  
Sequence Method ◽  
Highly Correlated ◽  
Spontaneous Baroreflex ◽  
Sequence Techniques

Short-term blood pressure (BP) variability is limited by the arterial baroreflex. Methods for measuring the spontaneous baroreflex sensitivity (BRS) aim to quantify the gain of the transfer function between BP and pulse interval (PI) or the slope of the linear relationship between parallel BP and PI changes. These frequency-domain (spectral) and time-domain (sequence) techniques were tested in conscious mice equipped with telemetric devices. The autonomic relevance of these indexes was evaluated using pharmacological blockades. The significant changes of the spectral bandwidths resulting from the autonomic blockades were used to identify the low-frequency (LF) and high-frequency (HF) zones of interest. The LF gain was 1.45 ± 0.14 ms/mmHg, with a PI delay of 0.5 s. For the HF gain, the average values were 2.0 ± 0.19 ms/mmHg, with a null phase. LF and HF bands were markedly affected by atropine. On the same 51.2-s segments used for cross-spectral analysis, an average number of 26.4 ± 2.2 slopes were detected, and the average slope in resting mice was 4.4 ± 0.5 ms/mmHg. Atropine significantly reduced the slopes of the sequence method. BRS measurements obtained using the sequence technique were highly correlated to the spectral estimates. This study demonstrates the applicability of the recent methods used to estimate spontaneous BRS in mice. There was a vagal predominance in the baroreflex control of heart rate in conscious mice in the present conditions.

Intracoronary epinephrine attenuates baroreflex control of heart rate in the conscious dog

1984 ◽  
Vol 247 (2) ◽  
pp. R237-R245
Author(s):  
M. J. Holmberg ◽  
A. J. Gorman ◽  
K. G. Cornish ◽  
I. H. Zucker
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Arterial Blood Pressure ◽  
Mean Arterial Blood Pressure ◽  
Rate Curve ◽  
Arterial Baroreflex ◽  
Baroreflex Control ◽  
Conscious Dog ◽  
Arterial Blood ◽  
The Mean

In the present study, the reflex effects of low-dose (12.5-50 ng X kg-1 X min-1) intracoronary epinephrine infusion on the arterial baroreflex control of heart rate were studied. Mean arterial blood pressure-heart rate curves were constructed by changing mean arterial blood pressure with graded occlusions of the descending aorta and inferior vena cava. Intracoronary epinephrine increased left ventricular dP/dtmax by an average of 309 +/- 67.0 mmHg/s but did not alter resting mean arterial blood pressure or heart rate. Peak sensitivity, the maximum absolute slope along the mean arterial blood pressure-heart rate curve, and heart rate range were 32.7 +/- 3.2 and 26.7 +/- 2.5% less during intracoronary epinephrine compared with control, respectively. Intracoronary epinephrine did not alter the median, threshold, or saturation pressure of the mean arterial blood pressure-heart rate curve. Lidocaine block of the pericoronary nerves, which blocked the ventricular afferent pathway, eliminated the effects of intracoronary epinephrine on the arterial baroreflex. Atropine abolished the effects of intracoronary epinephrine on arterial baroreflex control of heart rate. We conclude that intracoronary epinephrine reflexly attenuates the arterial baroreflex control of heart rate in the conscious dog through activation of ventricular receptors. This response is mediated by cardiac parasympathetic efferents common to both reflex arcs.

Exercise training improves aortic depressor nerve sensitivity in rats with ischemia-induced heart failure

2006 ◽  
Vol 291 (6) ◽  
pp. H2801-H2806 ◽  
Author(s):  
Eduardo Rondon ◽  
Maria S. Brasileiro-Santos ◽  
Edson D. Moreira ◽  
Maria U. P. B. Rondon ◽  
Katt C. Mattos ◽  
...  
Keyword(s):  
Heart Failure ◽  
Blood Pressure ◽  
Exercise Training ◽  
Systolic Blood Pressure ◽  
Normal Control ◽  
Left Ventricular ◽  
Pulse Interval ◽  
Nerve Activity ◽  
Baroreflex Control ◽  
Aortic Depressor Nerve

Exercise training improves arterial baroreflex control in heart failure (HF) rabbits. However, the mechanisms involved in the amelioration of baroreflex control are unknown. We tested the hypothesis that exercise training would increase the afferent aortic depressor nerve activity (AODN) sensitivity in ischemic-induced HF rats. Twenty ischemic-induced HF rats were divided into trained ( n = 11) and untrained ( n = 9) groups. Nine normal control rats were also studied. Power spectral analysis of pulse interval, systolic blood pressure, renal sympathetic nerve activity (RSNA), and AODN were analyzed by means of autoregressive parametric spectral and cross-spectral algorithms. Spontaneous baroreflex sensitivity of heart rate (HR) and RSNA were analyzed during spontaneous variation of systolic blood pressure. Left ventricular end-diastolic pressure was higher in HF rats compared with that in the normal control group ( P = 0.0001). Trained HF rats had a peak oxygen uptake higher than untrained rats and similar to normal controls ( P = 0.01). Trained HF rats had lower low-frequency [1.8 ± 0.2 vs. 14.6 ± 3 normalized units (nu), P = 0.0003] and higher high-frequency (97.9 ± 0.2 vs. 85.0 ± 3 nu, P = 0.0005) components of pulse interval than untrained rats. Trained HF rats had higher spontaneous baroreceptor sensitivity of HR (1.19 ± 0.2 vs. 0.51 ± 0.1 ms/mmHg, P = 0.003) and RSNA [2.69 ± 0.4 vs. 1.29 ± 0.3 arbitrary units (au)/mmHg, P = 0.04] than untrained rats. In HF rats, exercise training increased spontaneous AODN sensitivity toward normal levels (trained HF rats, 1,791 ± 215; untrained HF rats, 1,150 ± 158; and normal control rats, 2,064 ± 327 au/mmHg, P = 0.05). In conclusion, exercise training improves AODN sensitivity in HF rats.

scholarly journals Arterial baroreflex control of sympathetic nerve activity and heart rate in patients with type 2 diabetes

2016 ◽  
Vol 311 (5) ◽  
pp. H1170-H1179 ◽  
Author(s):  
Seth W. Holwerda ◽  
Lauro C. Vianna ◽  
Robert M. Restaino ◽  
Kunal Chaudhary ◽  
Colin N. Young ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Type 2 Diabetes ◽  
Heart Rate ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Group Differences ◽  
Arterial Baroreflex ◽  
Nerve Activity ◽  
Baroreflex Control

Despite greater blood pressure reactivity to acute cardiovascular stressors and a higher prevalence of hypertension in type 2 diabetes (T2D) patients, limited information is available regarding arterial baroreflex (ABR) control in T2D. We hypothesized that ABR control of muscle sympathetic nerve activity (MSNA) and heart rate (HR) are attenuated in T2D patients. Seventeen T2D patients (50 ± 2 yr; 31 ± 1 kg/m2), 9 weight-matched controls (WM-CON, 46 ± 2 yr; 32 ± 2 kg/m2) and 10 lean controls (Lean-CON, 49 ± 3 yr; 23 ± 1 kg/m2), underwent bolus infusions of sodium nitroprusside (100 μg) followed 60 s later by phenylephrine (150 μg) and weighted linear regression performed. No group differences in overall sympathetic baroreflex gain were observed (T2D: −2.5 ± 0.3 vs. WM-CON: −2.6 ± 0.2 vs. Lean-CON: −2.7 ± 0.4 arbitrary units·beat·mmHg−1, P > 0.05) or in sympathetic baroreflex gain when derived separately during blood pressure (BP) falls (nitroprusside) and BP rises (phenylephrine). In contrast, overall cardiac baroreflex gain was reduced in T2D patients compared with Lean-CON (T2D: 8.2 ± 1.5 vs. Lean-CON: 15.6 ± 2.9 ms·mmHg−1, P < 0.05) and also tended to be reduced in WM-CON (9.3 ± 1.9 ms·mmHg−1) compared with Lean-CON ( P = 0.059). Likewise, during BP rises, cardiac baroreflex gain was reduced in T2D patients and weight-matched controls compared with lean controls ( P < 0.05), whereas no group differences were found during BP falls ( P > 0.05). Sympathetic and cardiac ABR gains were comparable between normotensive and hypertensive T2D patients ( P > 0.05). These findings suggest preserved ABR control of MSNA in T2D patients compared with both obese and lean age-matched counterparts, with a selective impairment in ABR HR control in T2D that may be related to obesity.

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