scholarly journals Single-unit muscle sympathetic nervous activity and its relation to cardiac noradrenaline spillover

2011 ◽  
Vol 589 (10) ◽  
pp. 2597-2605 ◽  
Author(s):  
Elisabeth A. Lambert ◽  
Markus P. Schlaich ◽  
Tye Dawood ◽  
Carolina Sari ◽  
Reena Chopra ◽  
...  
Keyword(s):  
Single Unit ◽  
Nervous Activity ◽  
Sympathetic Nervous Activity ◽  
Muscle Sympathetic Nervous Activity ◽  
Sympathetic Nervous

Activation of the carotid chemoreflex secondary to muscle metaboreflex stimulation in men

2014 ◽  
Vol 306 (9) ◽  
pp. R693-R700 ◽  
Author(s):  
H. Edgell ◽  
M. K. Stickland
Keyword(s):  
Nervous Activity ◽  
Random Order ◽  
Voluntary Contraction ◽  
Sympathetic Nervous Activity ◽  
Muscle Metaboreflex ◽  
Healthy Men ◽  
Sympathetic Control ◽  
Muscle Sympathetic Nervous Activity ◽  
Sympathetic Nervous ◽  
Stimulation Of

Recent work has shown that the carotid chemoreceptor (CC) contributes to sympathetic control of cardiovascular function during exercise, despite no evidence of increased circulating CC stimuli, suggesting enhanced CC activity/sensitivity. As interactions between metaboreceptors and chemoreceptors have been previously observed, the purpose of this study was to isolate the metaboreflex while acutely stimulating or inhibiting the CC to determine whether the metaboreflex increased CC activity/sensitivity. Fourteen young healthy men (height: 177.0 ± 2.1 cm, weight: 85.8 ± 5.5 kg, age: 24.6 ± 1.1 yr) performed three trials of 40% maximal voluntary contraction handgrip for 2 min, followed by 3 min of postexercise circulatory occlusion (PECO) to stimulate the metaboreflex. In random order, subjects either breathed room air, hypoxia (target SPo2 = 85%), or hyperoxia (FiO2 = 1.0) during the PECO to modulate the chemoreflex. After these trials, a resting hypoxia trial was conducted without handgrip or PECO. Ventilation (V̇e), heart rate (HR), blood pressure, and muscle sympathetic nervous activity (MSNA) data were continuously obtained. Relative to normoxic PECO, inhibition of the CC during hyperoxic PECO resulted in lower MSNA ( P = 0.038) and HR ( P = 0.021). Relative to normoxic PECO, stimulation of the CC during hypoxic PECO resulted in higher HR ( P < 0.001) and V̇e ( P < 0.001). The ventilatory and MSNA responses to hypoxic PECO were not greater than the sum of the responses to hypoxia and PECO individually, indicating that the CC are not sensitized during metaboreflex activation. These results demonstrate that stimulation of the metaboreflex activates, but does not sensitize the CC, and help explain the enhanced CC activity with exercise.

Norepinephrine clearance is increased during acute hypoxemia in humans

1991 ◽  
Vol 261 (5) ◽  
pp. H1659-H1664 ◽  
Author(s):  
U. Leuenberger ◽  
K. Gleeson ◽  
K. Wroblewski ◽  
S. Prophet ◽  
R. Zelis ◽  
...  
Keyword(s):  
Blood Flow ◽  
Vascular Resistance ◽  
Nervous Activity ◽  
Significant Rise ◽  
Sympathetic Nervous Activity ◽  
Plasma Norepinephrine ◽  
Muscle Sympathetic Nervous Activity ◽  
Sympathetic Nervous ◽  
Infusion Technique ◽  
Forearm Vascular Resistance

Acute hypoxemia leads to activation of the sympathetic nervous system (SNS), yet adrenergic vasoconstriction does not occur and venous plasma norepinephrine (NE) fails to rise as expected. To examine whether this dissociation between SNS tone and plasma NE is due to altered metabolism of NE, we measured arterial NE kinetics ([3H]NE infusion technique) and sympathetic nervous outflow to muscle (peroneal microneurography) during 25-30 min of hypoxemia (spontaneous breathing, mean O2 saturation 74%) in six healthy young men. During hypoxemia, muscle sympathetic nervous activity (MSNA) rose significantly from 12.2 +/- 3.3 to 18.6 +/- 3.5 bursts/min, and the total amplitude increased from 123 +/- 36 to 255 +/- 50 mm/min. NE spillover, an index of NE release at the sympathetic nerve terminals, rose from 1.66 +/- 0.30 to 2.33 +/- 0.40 nmol.min-1.m-2 (P = 0.014). However, NE clearance increased also from 0.99 +/- 0.05 to 1.19 +/- 0.11 l.min-1.m-2 (P = 0.014), and arterial NE rose from 281 +/- 50 to 339 +/- 64 pg/ml (P = 0.023). Hypoxemia resulted in a significant rise in forearm blood flow and a decrease in forearm vascular resistance. The fact that skin blood flow and vascular resistance did not change implies that forearm vasodilation was localized to skeletal muscle. Our results suggest that during acute hypoxemia in humans the SNS is activated but the rise in plasma NE is attenuated because NE clearance is increased.

Muscle sympathetic nervous activity in depressed patients before and after treatment with sertraline

2009 ◽  
Vol 27 (12) ◽  
pp. 2429-2436 ◽  
Author(s):  
Andréia Zavaloni Scalco ◽  
Maria UPB Rondon ◽  
Ivani Credidio Trombetta ◽  
Mateus Camaroti Laterza ◽  
João BCCS Azul ◽  
...  
Keyword(s):  
Nervous Activity ◽  
Sympathetic Nervous Activity ◽  
Depressed Patients ◽  
Muscle Sympathetic Nervous Activity ◽  
Before And After ◽  
Sympathetic Nervous

Sympathetic nervous activity in carriers of MC4R mutations

2006 ◽  
Vol 114 (S 1) ◽  
Author(s):  
D Heutling ◽  
F Sayk ◽  
C Dodt ◽  
HL Fehm ◽  
A Hinney ◽  
...  
Keyword(s):  
Nervous Activity ◽  
Sympathetic Nervous Activity ◽  
Sympathetic Nervous
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