Differential arterial baroreflex regulation of renal, lumbar, and adrenal sympathetic nerve activity in the rat

1998 ◽  
Vol 275 (4) ◽  
pp. R995-R1002 ◽  
Author(s):  
Tadeusz J. Scislo ◽  
Robert A. Augustyniak ◽  
Donal S. O’Leary
Keyword(s):  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Full Range ◽  
Arterial Baroreflex ◽  
Response Curves ◽  
Regional Variability ◽  
Maximal Inhibition ◽  
Nerve Activity ◽  
Baroreflex Control ◽  
Stimulus Response

Lumbar (LSNA), renal (RSNA), or adrenal sympathetic nerve activity (ASNA) is most commonly used as an index of sympathetic nerve activity in investigations of arterial baroreflex control in the rat. Although differential regulation of sympathetic outputs to different organs has been extensively studied, no direct and simultaneous comparisons of the full range of baroreflex reactivity have been described for these sympathetic outputs. Therefore, we compared steady-state sigmoidal baroreflex stimulus-response curves (via phenylephrine-nitroprusside infusion) for RSNA recorded simultaneously with LSNA or ASNA in urethan-chloralose-anesthetized male Sprague-Dawley rats. Characteristics of the baroreflex curves differed significantly between all three sympathetic outputs. ASNA exhibited the greatest range of baroreflex regulation, the highest upper level of activity, and the widest distribution of the gain over a broad range of mean arterial pressure (MAP). RSNA exhibited greater gain than LSNA. LSNA showed the smallest range and maximal inhibition in comparison to other sympathetic outputs. However, all three nerves responded similarly to baroreflex stimulation and unloading in the range in MAP close to the operating point. We conclude that baroreflex regulation of sympathetic activity shows wide regional variability in gain, range, and maximal inhibition. Therefore, the entire stimulus-response relationship should be considered in comparing regional sympathetic responses.

scholarly journals Water drinking enhances the gain of arterial baroreflex control of muscle sympathetic nerve activity in healthy young humans

2018 ◽  
Vol 103 (10) ◽  
pp. 1318-1325 ◽  
Author(s):  
Lauro C. Vianna ◽  
Igor A. Fernandes ◽  
Daniel G. Martinez ◽  
André L. Teixeira ◽  
Bruno M. Silva ◽  
...  
Keyword(s):  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Muscle Sympathetic Nerve Activity ◽  
Arterial Baroreflex ◽  
Nerve Activity ◽  
Baroreflex Control ◽  
Water Drinking

scholarly journals Activation of NTS A2a adenosine receptors differentially resets baroreflex control of renal vs. adrenal sympathetic nerve activity

2009 ◽  
Vol 296 (4) ◽  
pp. H1058-H1068 ◽  
Author(s):  
Tomoko K. Ichinose ◽  
Donal S. O'Leary ◽  
Tadeusz J. Scislo
Keyword(s):  
Receptor Antagonist ◽  
Adenosine Receptors ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Response Curves ◽  
Nerve Activity ◽  
Baroreflex Control ◽  
A2a Adenosine Receptors ◽  
Stimulation Of

The role of nucleus of solitary tract (NTS) A2a adenosine receptors in baroreflex mechanisms is controversial. Stimulation of these receptors releases glutamate within the NTS and elicits baroreflex-like decreases in mean arterial pressure (MAP), heart rate (HR), and renal sympathetic nerve activity (RSNA), whereas inhibition of these receptors attenuates HR baroreflex responses. In contrast, stimulation of NTS A2a adenosine receptors increases preganglionic adrenal sympathetic nerve activity (pre-ASNA), and the depressor and sympathoinhibitory responses are not markedly affected by sinoaortic denervation and blockade of NTS glutamatergic transmission. To elucidate the role of NTS A2a adenosine receptors in baroreflex function, we compared full baroreflex stimulus-response curves for HR, RSNA, and pre-ASNA (intravenous nitroprusside/phenylephrine) before and after bilateral NTS microinjections of selective adenosine A2a receptor agonist (CGS-21680; 2.0, 20 pmol/50 nl), selective A2a receptor antagonist (ZM-241385; 40 pmol/100 nl), and nonselective A1 + A2a receptor antagonist (8-SPT; 1 nmol/100 nl) in urethane/α-chloralose anesthetized rats. Activation of A2a receptors decreased the range, upper plateau, and gain of baroreflex-response curves for RSNA, whereas these parameters all increased for pre-ASNA, consistent with direct effects of the agonist on regional sympathetic activity. However, no resetting of baroreflex-response curves along the MAP axis occurred despite the marked decreases in baseline MAP. The antagonists had no marked effects on baseline variables or baroreflex-response functions. We conclude that the activation of NTS A2a adenosine receptors differentially alters baroreflex control of HR, RSNA, and pre-ASNA mostly via non-baroreflex mechanism(s), and these receptors have virtually no tonic action on baroreflex control of these sympathetic outputs.

scholarly journals Arterial Baroreflex Control of Multi‐ and Single‐Unit Muscle Sympathetic Nerve Activity in Young Unmedicated Hypertensives

2019 ◽  
Vol 33 (S1) ◽  
Author(s):  
Anthony V Incognito ◽  
Milena Samora ◽  
Andrew D Shepherd ◽  
Roberta A Cartafina ◽  
Gabriel MN Guimarães ◽  
...  
Keyword(s):  
Sympathetic Nerve ◽  
Single Unit ◽  
Sympathetic Nerve Activity ◽  
Muscle Sympathetic Nerve Activity ◽  
Arterial Baroreflex ◽  
Nerve Activity ◽  
Baroreflex Control

scholarly journals Arterial baroreflex control of sympathetic nerve activity in multiple sclerosis

2009 ◽  
Vol 23 (S1) ◽  
Author(s):  
Scott L Davis ◽  
David M Keller ◽  
Paul J Fadel ◽  
Gina M Remington ◽  
Melissa A Korkmas ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Arterial Baroreflex ◽  
Nerve Activity ◽  
Baroreflex Control

Static handgrip exercise modifies arterial baroreflex control of vascular sympathetic outflow in humans

2001 ◽  
Vol 281 (4) ◽  
pp. R1134-R1139 ◽  
Author(s):  
Atsunori Kamiya ◽  
Daisaku Michikami ◽  
Qi Fu ◽  
Yuki Niimi ◽  
Satoshi Iwase ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Arterial Baroreflex ◽  
Static Exercise ◽  
Handgrip Exercise ◽  
Nerve Activity ◽  
Baroreflex Control ◽  
Diastolic Arterial Pressure ◽  
The Relationship

To examine effects of static exercise on the arterial baroreflex control of vascular sympathetic nerve activity, 22 healthy male volunteers performed 2 min of static handgrip exercise at 30% of maximal voluntary force, followed by postexercise circulatory arrest (PE-CA). Microneurographic recording of muscle sympathetic nerve activity (MSNA) was made with simultaneous recording of arterial pressure (Portapres). The relationship between MSNA and diastolic arterial pressure was calculated for each condition and was defined as the arterial baroreflex function. There was a close relationship between MSNA and diastolic arterial pressure in each subject at rest and during static exercise and PE-CA. The slope of the relationship significantly increased by >300% during static exercise ( P < 0.001), and the x-axis intercept (diastolic arterial pressure level) increased by 13 mmHg during exercise ( P< 0.001). These alterations in the baroreflex relationship were completely maintained during PE-CA. It is concluded that static handgrip exercise is associated with a resetting of the operating range and an increase in the reflex gain of the arterial barorelex control of MSNA.

scholarly journals Exercise training prevents the deterioration in the arterial baroreflex control of sympathetic nerve activity in chronic heart failure patients

2015 ◽  
Vol 308 (9) ◽  
pp. H1096-H1102 ◽  
Author(s):  
Raphaela V. Groehs ◽  
Edgar Toschi-Dias ◽  
Ligia M. Antunes-Correa ◽  
Patrícia F. Trevizan ◽  
Maria Urbana P. B. Rondon ◽  
...  
Keyword(s):  
Heart Failure ◽  
Time Delay ◽  
Exercise Training ◽  
Arterial Pressure ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Muscle Sympathetic Nerve Activity ◽  
Arterial Baroreflex ◽  
Nerve Activity ◽  
Baroreflex Control

Arterial baroreflex control of muscle sympathetic nerve activity (ABRMSNA) is impaired in chronic systolic heart failure (CHF). The purpose of the study was to test the hypothesis that exercise training would improve the gain and reduce the time delay of ABRMSNA in CHF patients. Twenty-six CHF patients, New York Heart Association Functional Class II-III, EF ≤ 40%, peak V̇o2 ≤ 20 ml·kg−1·min−1 were divided into two groups: untrained (UT, n = 13, 57 ± 3 years) and exercise trained (ET, n = 13, 49 ± 3 years). Muscle sympathetic nerve activity (MSNA) was directly recorded by microneurography technique. Arterial pressure was measured on a beat-to-beat basis. Time series of MSNA and systolic arterial pressure were analyzed by autoregressive spectral analysis. The gain and time delay of ABRMSNA was obtained by bivariate autoregressive analysis. Exercise training was performed on a cycle ergometer at moderate intensity, three 60-min sessions per week for 16 wk. Baseline MSNA, gain and time delay of ABRMSNA, and low frequency of MSNA (LFMSNA) to high-frequency ratio (HFMSNA) (LFMSNA/HFMSNA) were similar between groups. ET significantly decreased MSNA. MSNA was unchanged in the UT patients. The gain and time delay of ABRMSNA were unchanged in the ET patients. In contrast, the gain of ABRMSNA was significantly reduced [3.5 ± 0.7 vs. 1.8 ± 0.2, arbitrary units (au)/mmHg, P = 0.04] and the time delay of ABRMSNA was significantly increased (4.6 ± 0.8 vs. 7.9 ± 1.0 s, P = 0.05) in the UT patients. LFMSNA-to-HFMSNA ratio tended to be lower in the ET patients ( P < 0.08). Exercise training prevents the deterioration of ABRMSNA in CHF patients.

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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