scholarly journals Detection of low- and high-frequency rhythms in the variability of skin sympathetic nerve activity

2000 ◽  
Vol 278 (4) ◽  
pp. H1256-H1260 ◽  
Author(s):  
Chiara Cogliati ◽  
Renata Magatelli ◽  
Nicola Montano ◽  
Krzysztof Narkiewicz ◽  
Virend K. Somers
Keyword(s):  
Blood Flow ◽  
Spectral Analysis ◽  
Skin Blood Flow ◽  
Sympathetic Nerve ◽  
High Frequency ◽  
Sympathetic Nerve Activity ◽  
Muscle Sympathetic Nerve Activity ◽  
Systolic Pressure ◽  
Nerve Activity ◽  
Skin Sympathetic Nerve Activity

Spectral analysis of skin blood flow has demonstrated low-frequency (LF, 0.03–0.15 Hz) and high-frequency (HF, 0.15–0.40 Hz) oscillations, similar to oscillations in R-R interval, systolic pressure, and muscle sympathetic nerve activity (MSNA). It is not known whether the oscillatory profile of skin blood flow is secondary to oscillations in arterial pressure or to oscillations in skin sympathetic nerve activity (SSNA). MSNA and SSNA differ markedly with regard to control mechanisms and morphology. MSNA contains vasoconstrictor fibers directed to muscle vasculature, closely regulated by baroreceptors. SSNA contains both vasomotor and sudomotor fibers, differentially responding to arousals and thermal stimuli. Nevertheless, MSNA and SSNA share certain common characteristics. We tested the hypothesis that LF and HF oscillatory components are evident in SSNA, similar to the oscillatory components present in MSNA. We studied 18 healthy normal subjects and obtained sequential measurements of MSNA and SSNA from the peroneal nerve during supine rest. Measurements were also obtained of the electrocardiogram, beat-by-beat blood pressure (Finapres), and respiration. Spectral analysis showed LF and HF oscillations in MSNA, coherent with similar oscillations in both R-R interval and systolic pressure. The HF oscillation of MSNA was coherent with respiration. Similarly, LF and HF spectral components were evident in SSNA variability, coherent with corresponding variability components of R-R interval and systolic pressure. HF oscillations of SSNA were coherent with respiration. Thus our data suggest that these oscillations may be fundamental characteristics shared by MSNA and SSNA, possibly reflecting common central mechanisms regulating sympathetic outflows subserving different regions and functions.

Spectral characteristics of skin sympathetic nerve activity in heat-stressed humans

2006 ◽  
Vol 290 (4) ◽  
pp. H1601-H1609 ◽  
Author(s):  
Jian Cui ◽  
Mithra Sathishkumar ◽  
Thad E. Wilson ◽  
Manabu Shibasaki ◽  
Scott L. Davis ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Heat Stress ◽  
Skin Blood Flow ◽  
Sympathetic Nerve ◽  
High Frequency ◽  
Sympathetic Nerve Activity ◽  
Spectral Power ◽  
Spectral Characteristics ◽  
Nerve Activity

Skin sympathetic nerve activity (SSNA) exhibits low- and high-frequency spectral components in normothermic subjects. However, spectral characteristics of SSNA in heat-stressed subjects are unknown. Because the main components of the integrated SSNA during heat stress (sudomotor/vasodilator activities) are different from those during normothermia and cooling (vasoconstrictor activity), we hypothesize that spectral characteristics of SSNA in heat-stressed subjects will be different from those in subjects subjected to normothermia or cooling. In 17 healthy subjects, SSNA, electrocardiogram, arterial blood pressure (via Finapres), respiratory activity, and skin blood flow were recorded during normothermia and heat stress. In 7 of the 17 subjects, these variables were also recorded during cooling. Spectral characteristics of integrated SSNA, R-R interval, beat-by-beat mean blood pressure, skin blood flow variability, and respiratory excursions were assessed. Heat stress and cooling significantly increased total SSNA. SSNA spectral power in the low-frequency (0.03–0.15 Hz), high-frequency (0.15–0.45 Hz), and very-high-frequency (0.45–2.5 Hz) regions was significantly elevated by heat stress and cooling. Interestingly, heat stress caused a greater relative increase of SSNA spectral power within the 0.45- to 2.5-Hz region than in the other spectral ranges; cooling did not show this effect. Differences in the SSNA spectral distribution between normothermia/cooling and heat stress may reflect different characteristics of central modulation of vasoconstrictor and sudomotor/vasodilator activities.

Changes in Skin Blood Flow and Skin Sympathetic Nerve Activity in Response to Manual Acupuncture Stimulation in Humans

2006 ◽  
Vol 34 (02) ◽  
pp. 189-196 ◽  
Author(s):  
Kenichi Kimura ◽  
Kenichi Masuda ◽  
Ikuro Wakayama
Keyword(s):  
Blood Flow ◽  
Skin Blood Flow ◽  
Negative Correlation ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Acupuncture Group ◽  
Control Group ◽  
Manual Acupuncture ◽  
Nerve Activity ◽  
Skin Sympathetic Nerve Activity

To determine the effects of manual acupuncture stimulation (MAS) on skin sympathetic nerve activity (SSNA), SSNA and skin blood flow (SBF) were measured during a resting period and during MAS. Twelve healthy male subjects were divided into an acupuncture group ( n = 7) and a control group ( n = 5). SSNA was recorded from the left median nerve at the elbow using microneurography, while SBF was recorded using laser Doppler flowmeter. In the acupuncture group, MAS was delivered to LI 4 point in the right thenar muscle. The acupuncture needle was retained for 2 minutes before being removed. SSNA and SBF recordings were performed for a total of 12 minutes, from 5 minutes prior to MAS until the end of the trial. In the control group, the 2-minute period of acupuncture was replaced by 2 minutes of rest. During the first minute of MAS, we observed an increase in SSNA accompanied by a reduction in SBF. In the acupuncture group, these parameters returned to baseline values in the second minute of MAS. Parameters in the control group were unchanged throughout the experimental procedure. A significant negative correlation was observed between changes in SSNA and SBF during the first minute of MAS. In addition, a negative correlation was demonstrated between the basal value of SSNA and the change in SSNA in response to MAS. These results suggest that MAS elicited a transient increase in SSNA and that this increase is dependent on the baseline of SSNA.

scholarly journals Hypoxia-induced vasodilation and effects of regional phentolamine in awake patients with sleep apnea

2010 ◽  
Vol 108 (5) ◽  
pp. 1234-1240 ◽  
Author(s):  
Raman Moradkhan ◽  
Brett Spitnale ◽  
Patrick McQuillan ◽  
Cynthia Hogeman ◽  
Kristen S. Gray ◽  
...  
Keyword(s):  
Blood Flow ◽  
Sleep Apnea ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Muscle Sympathetic Nerve Activity ◽  
Acute Hypoxia ◽  
Artery Blood Flow ◽  
Nerve Activity ◽  
Premature Cardiovascular Disease ◽  
Obstructive Sleep

Obstructive sleep apnea (OSA) is associated with increased sympathetic nerve activity, endothelial dysfunction, and premature cardiovascular disease. To determine whether hypoxia is associated with impaired skeletal muscle vasodilation, we compared femoral artery blood flow (ultrasound) and muscle sympathetic nerve activity (peroneal microneurography) during exposure to acute systemic hypoxia (fraction of inspired oxygen 0.1) in awake patients with OSA ( n = 10) and controls ( n = 8). To assess the role of elevated sympathetic nerve activity, in a separate group of patients with OSA ( n = 10) and controls ( n = 10) we measured brachial artery blood flow during hypoxia before and after regional α-adrenergic block with phentolamine. Despite elevated sympathetic activity, in OSA the vascular responses to hypoxia in the leg did not differ significantly from those in controls [ P = not significant (NS)]. Following regional phentolamine, in both groups the hypoxia-induced increase in brachial blood flow was markedly enhanced (OSA pre vs. post, 84 ± 13 vs. 201 ± 34 ml/min, P < 0.002; controls pre vs. post 62 ± 8 vs. 140 ± 26 ml/min, P < 0.01). At end hypoxia after phentolamine, the increase of brachial blood flow above baseline was similar (OSA vs. controls +61 ± 16 vs. +48 ± 6%; P = NS). We conclude that despite high sympathetic vasoconstrictor tone and prominent sympathetic responses to acute hypoxia, hypoxia-induced limb vasodilation is preserved in OSA.

Spectral analysis of heart rate, arterial pressure, and muscle sympathetic nerve activity in normal humans

1998 ◽  
Vol 274 (4) ◽  
pp. H1211-H1217 ◽  
Author(s):  
Akio Nakata ◽  
Shigeo Takata ◽  
Toyoshi Yuasa ◽  
Atsuhiro Shimakura ◽  
Michiro Maruyama ◽  
...  
Keyword(s):  
Heart Rate ◽  
Spectral Analysis ◽  
Arterial Pressure ◽  
Sympathetic Nerve ◽  
Autoregressive Model ◽  
Sympathetic Nerve Activity ◽  
Muscle Sympathetic Nerve Activity ◽  
Model Fitting ◽  
Power Spectral Analysis ◽  
Nerve Activity

We investigated the frequency components of fluctuations in heart rate, arterial pressure, respiration, and muscle sympathetic nerve activity (MSNA) in 11 healthy women using an autoregressive model and examined the relation among variables using Akaike’s relative power contribution analysis with multivariate autoregressive model fitting. Power spectral analysis of MSNA revealed two peaks, with low-frequency (LF) and high-frequency (HF) components. The LF component of MSNA was a major determinant of the LF component of arterial pressure and R-R interval variability (0.70 ± 0.07 and 0.18 ± 0.05, respectively). The effect of the LF component of MSNA on arterial pressure showed no change in response to propranolol but was diminished (0.35 ± 0.08) by phentolamine ( P < 0.02). The effect of the LF component of MSNA on R-R interval was not altered by pharmacological sympathetic nerve blockade. The HF component of MSNA did not influence other variables but was influenced by R-R interval, arterial pressure, and respiration. These findings indicate that the LF component of MSNA reflects autonomic oscillations, whereas the HF component is passive and influenced by other cardiovascular variables.

scholarly journals Transcranial Doppler estimation of cerebral blood flow and cerebrovascular conductance during modified rebreathing

2007 ◽  
Vol 102 (3) ◽  
pp. 870-877 ◽  
Author(s):  
Jurgen A. H. R. Claassen ◽  
Rong Zhang ◽  
Qi Fu ◽  
Sarah Witkowski ◽  
Benjamin D. Levine
Keyword(s):  
Blood Flow ◽  
Logistic Regression ◽  
Cerebral Blood Flow ◽  
Linear Regression ◽  
Transcranial Doppler ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Muscle Sympathetic Nerve Activity ◽  
Arterial Oxygen ◽  
Nerve Activity

Clinical transcranial Doppler assessment of cerebral vasomotor reactivity (CVMR) uses linear regression of cerebral blood flow velocity (CBFV) vs. end-tidal CO2 (PetCO2) under steady-state conditions. However, the cerebral blood flow (CBF)-PetCO2 relationship is nonlinear, even for moderate changes in CO2. Moreover, CBF is increased by increases in arterial blood pressure (ABP) during hypercapnia. We used a modified rebreathing protocol to estimate CVMR during transient breath-by-breath changes in CBFV and PetCO2. Ten healthy subjects (6 men) performed 15 s of hyperventilation followed by 5 min of rebreathing, with supplemental O2 to maintain arterial oxygen saturation constant. To minimize effects of changes in ABP on CVMR estimation, cerebrovascular conductance index (CVCi) was calculated. CBFV-PetCO2 and CVCi-PetCO2 relationships were quantified by both linear and nonlinear logistic regression. In three subjects, muscle sympathetic nerve activity was recorded. From hyperventilation to rebreathing, robust changes occurred in PetCO2 (20–61 Torr), CBFV (−44 to +104% of baseline), CVCi (−39 to +64%), and ABP (−19 to +23%) (all P < 0.01). Muscle sympathetic nerve activity increased by 446% during hypercapnia. The linear regression slope of CVCi vs. PetCO2 was less steep than that of CBFV (3 vs. 5%/Torr; P = 0.01). Logistic regression of CBF-PetCO2 ( r2 = 0.97) and CVCi-PetCO2 ( r2 = 0.93) was superior to linear regression ( r2 = 0.91, r2 = 0.85; P = 0.01). CVMR was maximal (6–8%/Torr) for PetCO2 of 40–50 Torr. In conclusion, CBFV and CVCi responses to transient changes in PetCO2 can be described by a nonlinear logistic function, indicating that CVMR estimation varies within the range from hypocapnia to hypercapnia. Furthermore, quantification of the CVCi-PetCO2 relationship may minimize the effects of changes in ABP on the estimation of CVMR. The method developed provides insight into CVMR under transient breath-by-breath changes in CO2.

Sign in / Sign up

Export Citation Format

Share Document