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.

scholarly journals Augmented supraorbital skin sympathetic nerve activity responses to symptom trigger events in rosacea patients

2015 ◽  
Vol 114 (3) ◽  
pp. 1530-1537 ◽  
Author(s):  
Kristen Metzler-Wilson ◽  
Kumika Toma ◽  
Dawn L. Sammons ◽  
Sarah Mann ◽  
Andrew J. Jurovcik ◽  
...  
Keyword(s):  
Blood Flow ◽  
Heat Stress ◽  
Skin Blood Flow ◽  
Water Loss ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Local Heating ◽  
Nerve Activity ◽  
Axon Reflex ◽  
Trigger Events

Facial flushing in rosacea is often induced by trigger events. However, trigger causation mechanisms are currently unclear. This study tested the central hypothesis that rosacea causes sympathetic and axon reflex-mediated alterations resulting in trigger-induced symptomatology. Twenty rosacea patients and age/sex-matched controls participated in one or a combination of symptom triggering stressors. In protocol 1, forehead skin sympathetic nerve activity (SSNA; supraorbital microneurography) was measured during sympathoexcitatory mental (2-min serial subtraction of novel numbers) and physical (2-min isometric handgrip) stress. In protocol 2, forehead skin blood flow (laser-Doppler flowmetry) and transepithelial water loss/sweat rate (capacitance hygrometry) were measured during sympathoexcitatory heat stress (whole body heating by perfusing 50°C water through a tube-lined suit). In protocol 3, cheek, forehead, forearm, and palm skin blood flow were measured during nonpainful local heating to induce axon reflex vasodilation. Heart rate (HR) and mean arterial pressure (MAP) were recorded via finger photoplethysmography to calculate cutaneous vascular conductance (CVC; flux·100/MAP). Higher patient transepithelial water loss was observed (rosacea 0.20 ± 0.02 vs. control 0.10 ± 0.01 mg·cm−2·min−1, P < 0.05). HR and MAP changes were not different between groups during sympathoexcitatory stressors or local heating. SSNA during early mental (32 ± 9 and 9 ± 4% increase) and physical (25 ± 4 and 5 ± 1% increase, rosacea and controls, respectively) stress was augmented in rosacea (both P < 0.05). Heat stress induced more rapid sweating and cutaneous vasodilation onset in rosacea compared with controls. No axon reflex vasodilation differences were observed between groups. These data indicate that rosacea affects SSNA and that hyperresponsiveness to trigger events appears to have a sympathetic component.

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.

Cardiopulmonary baroreceptor control of muscle sympathetic nerve activity in heat-stressed humans

1999 ◽  
Vol 277 (6) ◽  
pp. H2348-H2352 ◽  
Author(s):  
C. G. Crandall ◽  
R. A. Etzel ◽  
D. B. Farr
Keyword(s):  
Blood Pressure ◽  
Heat Stress ◽  
Arterial Blood Pressure ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Muscle Sympathetic Nerve Activity ◽  
Venous Pressure ◽  
Whole Body ◽  
Nerve Activity ◽  
Arterial Blood

Whole body heating decreases central venous pressure (CVP) while increasing muscle sympathetic nerve activity (MSNA). In normothermia, similar decreases in CVP elevate MSNA, presumably via cardiopulmonary baroreceptor unloading. The purpose of this project was to identify whether increases in MSNA during whole body heating could be attributed to cardiopulmonary baroreceptor unloading coincident with the thermal challenge. Seven subjects were exposed to whole body heating while sublingual temperature, skin blood flow, heart rate, arterial blood pressure, and MSNA were monitored. During the heat stress, 15 ml/kg warmed saline was infused intravenously over 7–10 min to increase CVP and load the cardiopulmonary baroreceptors. We reported previously that this amount of saline was sufficient to return CVP to pre-heat stress levels. Whole body heating increased MSNA from 25 ± 3 to 39 ± 3 bursts/min ( P < 0.05). Central blood volume expansion via rapid saline infusion did not significantly decrease MSNA (44 ± 4 bursts/min, P > 0.05 relative to heat stress period) and did not alter mean arterial blood pressure (MAP) or pulse pressure. To identify whether arterial baroreceptor loading decreases MSNA during heat stress, in a separate protocol MAP was elevated via steady-state infusion of phenylephrine during whole body heating. Increasing MAP from 82 ± 3 to 93 ± 4 mmHg ( P < 0.05) caused MSNA to decrease from 36 ± 3 to 15 ± 4 bursts/min ( P < 0.05). These data suggest that cardiopulmonary baroreceptor unloading during passive heating is not the primary mechanism resulting in elevations in MSNA. Moreover, arterial baroreceptors remain capable of modulating MSNA during heat stress.

Baroreflex modulation of sympathetic nerve activity to muscle in heat-stressed humans

2002 ◽  
Vol 282 (1) ◽  
pp. R252-R258 ◽  
Author(s):  
Jian Cui ◽  
Thad E. Wilson ◽  
Craig G. Crandall
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Heat Stress ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Whole Body ◽  
Arterial Baroreflex ◽  
Nerve Activity ◽  
Arterial Blood ◽  
The Relationship

To identify whether whole body heating alters arterial baroreflex control of muscle sympathetic nerve activity (MSNA), MSNA and beat-by-beat arterial blood pressure were recorded in seven healthy subjects during acute hypotensive and hypertensive stimuli in both normothermic and heat stress conditions. Whole body heating significantly increased sublingual temperature ( P < 0.01), MSNA ( P < 0.01), heart rate ( P< 0.01), and skin blood flow ( P < 0.001), whereas mean arterial blood pressure did not change significantly ( P > 0.05). During both normothermic and heat stress conditions, MSNA increased and then decreased significantly when blood pressure was lowered and then raised via intravenous bolus infusions of sodium nitroprusside and phenylephrine HCl, respectively. The slope of the relationship between MSNA and diastolic blood pressure during heat stress (−128.3 ± 13.9 U · beats−1 · mmHg−1) was similar ( P = 0.31) with normothermia (−140.6 ± 21.1 U · beats−1 · mmHg−1). Moreover, no significant change in the slope of the relationship between heart rate and systolic blood pressure was observed. These data suggest that arterial baroreflex modulation of MSNA and heart rate are not altered by whole body heating, with the exception of an upward shift of these baroreflex curves to accommodate changes in these variables that occur with whole body heating.

Neural control of muscle blood flow during exercise

2004 ◽  
Vol 97 (2) ◽  
pp. 731-738 ◽  
Author(s):  
Gail D. Thomas ◽  
Steven S. Segal
Keyword(s):  
Blood Pressure ◽  
Skeletal Muscle ◽  
Blood Flow ◽  
Arterial Blood Pressure ◽  
Sympathetic Nerve ◽  
Neural Control ◽  
Sympathetic Nerve Activity ◽  
Muscle Blood Flow ◽  
Nerve Activity ◽  
Arterial Blood

Activation of skeletal muscle fibers by somatic nerves results in vasodilation and functional hyperemia. Sympathetic nerve activity is integral to vasoconstriction and the maintenance of arterial blood pressure. Thus the interaction between somatic and sympathetic neuroeffector pathways underlies blood flow control to skeletal muscle during exercise. Muscle blood flow increases in proportion to the intensity of activity despite concomitant increases in sympathetic neural discharge to the active muscles, indicating a reduced responsiveness to sympathetic activation. However, increased sympathetic nerve activity can restrict blood flow to active muscles to maintain arterial blood pressure. In this brief review, we highlight recent advances in our understanding of the neural control of the circulation in exercising muscle by focusing on two main topics: 1) the role of motor unit recruitment and muscle fiber activation in generating vasodilator signals and 2) the nature of interaction between sympathetic vasoconstriction and functional vasodilation that occurs throughout the resistance network. Understanding how these control systems interact to govern muscle blood flow during exercise leads to a clear set of specific aims for future research.

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.

EFFECTS OF EXERCISE ON BLOOD PRESSURE, SYMPATHETIC NERVE ACTIVITY, AND MUSCLE BLOOD FLOW RESPONSES TO HYPERINSULINEMIA IN MEN.

1998 ◽  
Vol 30 (Supplement) ◽  
pp. 213
Author(s):  
C. L.M. Forjaz ◽  
P. R. Ramires ◽  
T. Tinucci ◽  
K. C. Ortega ◽  
H. E.H. Salom??o ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Muscle Blood Flow ◽  
Nerve Activity
Sign in / Sign up

Export Citation Format

Share Document