Vestibular activation does not influence skin sympathetic nerve responses during whole body heating

Wilson, Thad E.; Kuipers, Nathan T.; McHugh, Erica A.; Ray, Chester A.

doi:10.1152/japplphysiol.00174.2004

Cited by 13 publications

(20 citation statements)

References 41 publications

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“…Sympathetic nerve recordings that demonstrated possible electrode site shifts or electromyographic artifact were excluded from analysis (n ϭ 1; leaving 11 full SSNA data sets for the melatonin trial). Consistent with previous experiments in our laboratory (23,26,35,36) and others (18,32,34), SSNA was expressed as a percent change in total area under the mean voltage neurogram relative to the preceding baseline (5 min average). This analysis was achieved using computer software (Chart 5, ADInstruments), and the focus was on the first 10 s of mental stress Values are means Ϯ SE; for the melatonin trials, n ϭ 11, and for placebo, n ϭ 8.…”

Section: Subjectsmentioning

confidence: 69%

“…Once the recording nerve site was established, two skin blood flow lasers (Moor Instruments, local heater set at 34°C) and one thermocouple were carefully attached to the dorsal foot (within the region of innervation on the foot) (28,31,36). Sweat rate was measured on the contralateral dorsal foot via capacitance hygrometry (Vaisala, Woburn, MA) by perfusing 100% nitrogen at a flow rate of 150 ml/min through a ventilated capsule (surface area, 2.0 cm 2 ).…”

Section: Subjectsmentioning

confidence: 99%

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Melatonin attenuates the skin sympathetic nerve response to mental stress

Muller

Sauder

Ray

2013

American Journal of Physiology-Heart and Circulatory Physiology

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Muller MD, Sauder CL, Ray CA. Melatonin attenuates the skin sympathetic nerve response to mental stress. Am J Physiol Heart Circ Physiol 305: H1382-H1386, 2013. First published August 30, 2013 doi:10.1152/ajpheart.00470.2013.-Melatonin attenuates muscle sympathetic nerve responses to sympathoexcitatory stimuli, but it is unknown whether melatonin similarly attenuates reflex changes in skin sympathetic nerve activity (SSNA). In this double-blind, placebo-controlled, crossover study, we tested the hypothesis that melatonin (3 mg) would attenuate the SSNA response to mental stress (mental arithmetic). Twelve healthy subjects underwent experimental testing on two separate days. Three minutes of mental stress occurred before and 45 min after ingestion of melatonin (3 mg) or placebo. Skin temperature was maintained at 34°C. Reflex increases in SSNA (peroneal nerve), mean arterial pressure, and heart rate (HR) to mental stress before and after melatonin were determined. Melatonin lowered HR (pre, 66 Ϯ 3 beats/min; and post, 62 Ϯ 3 beats/min, P ϭ 0.046) and SSNA (pre, 14,282 Ϯ 3,706 arbitrary units; and post, 9,571 Ϯ 2,609 arbitrary units, P ϭ 0.034) at rest. In response to mental stress, SSNA increases were significantly attenuated following melatonin ingestion (second minute, 114 Ϯ 30 vs. 74 Ϯ 14%; and third minute, 111 Ϯ 29 vs. 54 Ϯ 12%, both P Ͻ 0.05). The mean arterial pressure increase to mental stress was blunted in the third minute (20 Ϯ 2 vs. 17 Ϯ 2 mmHg, P ϭ 0.032), and the HR increase was blunted in the first minute (33 Ϯ 3 vs. 29 Ϯ 3 beats/min, P ϭ 0.034) after melatonin. In summary, exogenous melatonin attenuates the SSNA response to mental stress. autonomic nervous system; blood pressure; heart rate MELATONIN IS AN ENDOGENOUS hormone secreted by the pineal gland in a circadian rhythm. This hormone is mechanistically linked to the sleep-wake cycle, and peak plasma levels are evident in the early morning (1:00 to 5:00 AM) (19,27). For this reason, melatonin is commonly ingested in high doses to improve sleep (i.e., 3 to 5 mg, which leads to Ͼ50 times above physiological levels). In addition to its effectiveness as a sleep aid, mounting evidence suggests that exogenous melatonin has widespread effects on immune response, aging, and cancer (c.f., 7, 37). Furthermore, melatonin supplementation has been reported to reduce blood pressure in patients with metabolic syndrome (20) and essential hypertension (30). One mechanism by which melatonin decreases blood pressure could be its effect on cardiovascular reflexes.In previous studies, our laboratory demonstrated that melatonin attenuated increases in muscle sympathetic nerve activity (MSNA) to both lower body negative pressure (24) and headdown rotation (14). These findings suggest that melatonin attenuates reflex changes in sympathetic outflow during postural change. However, the effect of melatonin on reflex changes in skin sympathetic nerve activity (SSNA) is unknown. The interaction of melatonin on SSNA is important to understand because both participate in t...

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Section: Subjectsmentioning

confidence: 69%

Section: Subjectsmentioning

confidence: 99%

Melatonin attenuates the skin sympathetic nerve response to mental stress

Muller

Sauder

Ray

2013

American Journal of Physiology-Heart and Circulatory Physiology

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“…These results indicate that stimulation of the horizontal semicircular canals does not alter sympathetic nerve activity to either the muscle or skin. Wilson et al (42) has also reported no change in SSNA during yaw head rotation before and after whole body heating.…”

Section: Sympathetic Responses To Activation Of the Semicircular Canamentioning

confidence: 94%

Sympathetic responses to vestibular activation in humans

Carter¹,

Ray²

2008

American Journal of Physiology-Regulatory, Integrative and Comp

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Activation of sympathetic neural traffic via the vestibular system is referred to as the vestibulosympathetic reflex. Investigations of the vestibulosympathetic reflex in humans have been limited to the past decade, and the importance of this reflex in arterial blood pressure regulation is still being determined. This review provides a summary of sympathetic neural responses to various techniques used to engage the vestibulosympathetic reflex. Studies suggest that activation of the semicircular canals using caloric stimulation and yaw rotation do not modulate muscle sympathetic nerve activity (MSNA) or skin sympathetic nerve activity (SSNA). In contrast, activation of the otolith organs appear to alter MSNA, but not SSNA. Specifically, head-down rotation and off-vertical axis rotation increase MSNA, while sinusoidal linear accelerations decrease MSNA. Galvanic stimulation, which results in a nonspecific activation of the vestibule, appears to increase MSNA if the mode of delivery is pulse trained. In conclusion, evidence strongly supports the existence of a vestibulosympathetic reflex in humans. Furthermore, attenuation of the vestibulosympathetic reflex is coupled with a drop in arterial blood pressure in the elderly, suggesting this reflex may be important in human blood pressure regulation.

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“…Another factor that must be considered when discussing orthostatic tolerance during heat stress is that activation of the otolith organs does not contribute to skin vascular resistance during normothermia (23) and whole body heating (31). This could be problematic for orthostatic tolerance in the human, because large amounts of blood flow are being directed to the skin and reductions within this vascular space would be important to maintain arterial blood pressure, whereas the further constriction of an already vasoconstricted vascular bed (i.e., muscle) would be less essential.…”

Section: Discussionmentioning

confidence: 99%