Search results for "Sympathetic nervous system"
showing 10 items of 143 documents
The Effects of Sympathetic Inhibition on Metabolic and Cardiopulmonary Responses to Exercise in Hypoxic Conditions.
2015
Objective Pre-exertion skeletal muscle glycogen content is an important physiological determinant of endurance exercise performance: low glycogen stores contribute to premature fatigue. In low-oxygen environments (hypoxia), the important contribution of carbohydrates to endurance performance is further enhanced as glucose and glycogen dependence is increased; however, the insulin sensitivity of healthy adult humans is decreased. In light of this insulin resistance, maintaining skeletal muscle glycogen in hypoxia becomes difficult, and subsequent endurance performance is impaired. Sympathetic inhibition promotes insulin sensitivity in hypoxia but may impair hypoxic exercise performance, in p…
Clonidine induces nitric oxide- and prostaglandin-mediated vasodilation in healthy human skin
2005
Sustained sympathetic activation not only leads to vasoconstriction but also might induce paradox vasodilation. This study was performed to explore whether and how alpha(2)-receptor stimulation mediates this vasodilation. We investigated 11 healthy subjects in 33 dermal microdialysis (MD) sessions. After nerve trunk blockade, MD fibers were inserted and perfused with physiological saline until skin trauma-related vasodilation subsided. Thereafter, fibers were perfused with either clonidine solutions (10(-3), 5 x 10(-4), 10(-4) mol/l), N(G)-monomethyl-l-arginine (L-NMMA; nitric oxide synthase blocker), acetylsalicylic acid (ASA; cyclooxygenase blocker), or combinations of these. Laser-Dopple…
Depressive symptoms and attenuated physiological reactivity to laboratory stressors.
2010
There is evidence that depressive symptoms are associated with attenuated physiological reactivity to active stressors. However, it is not known whether blunted reactivity in depressed individuals is stressor-specific. We examined cardiovascular and electrodermal reactivity in non-clinical participants with varying levels of depressive symptoms to different active and passive stressors. Depressive symptoms were inversely related to both blood pressure and skin conductance reactivity during a public speaking task and the viewing of the speech video. However, no effects were found during a cold pressor task. Together these findings suggest that depressive symptoms are related to attenuated sy…
Comparison of the sympathetic skin response and continuous wave Doppler sonography of the radial artery.
1999
The value of neurophysiological tests of the autonomic nerve system is limited. One of the clinically most commonly applied test is the skin sudomotor response, frequently referred to as 'sympathetic skin response' (SSR). However, the SSR is a more qualitative than quantitative evaluation technique. Continuous wave (cw) Doppler sonography of the radial artery may be an alternative quantitative approach. We studied 41 age matched volunteers (23 female, 18 male; 16-82 years (mean age 53 years)). The stimulus was a loud and unexpected acoustic signal, alternatively a cough. SSR evaluation included the latency of onset, the duration and the amplitude of the response. Doppler evaluation also inc…
Stress and thermoregulation: different sympathetic responses and different effects on experimental pain.
2009
Stress and thermoregulation both activate the sympathetic nervous system (SNS) but might differently affect pain. Studies investigating possible interactions in patients are problematic because of the high prevalence of SNS disturbances in patients. We therefore analyzed the influence of these different sympathetic challenges on experimentally-induced pain in healthy subjects. SNS was activated in two different ways: by mental stress (Stroop task, mental arithmetic task), and by thermoregulatory stimulation using a water-perfused thermal suit (7 degrees C, 32 degrees C, or 50 degrees C). Attentional effects of the mental stress tasks were controlled by using easy control tasks. Both, stress…
Long-term urinary dysfunction after mesorectal excision: a prospective study with intraoperative electrophysiological confirmation of nerve preservat…
2006
Bladder dysfunctions are well-recognized complications after nerve-sparing mesorectal excision for rectal cancer. This study sought to symptomatically analyze the extent of recovery from major and minor urinary symptoms in patients with signs of bladder denervation.Sixty-two patients with mesorectal excision for rectal cancer were investigated prospectively. Pelvic autonomic nerve preservation (PANP) was assessed macroscopically and with the aid of intraoperative electrical stimulation of pelvic autonomic nerves (INS). Bladder function was evaluated with the International Prostate Symptom Score (IPSS) and the Quality of life index (Qol). Median follow-up was 20 months (range 3-40 months).Fo…
Validity of Pelvic Autonomic Nerve Stimulation With Intraoperative Monitoring of Bladder Function Following Total Mesorectal Excision for Rectal Canc…
2005
This prospective study was designed to clarify whether the results of the intraoperative stimulation of parasympathetic pelvic nerves performed in 31 patients after mesorectal excision for rectal carcinoma allowed predictions in terms of the postoperative bladder function of the patients.After monopolar stimulation of the splanchnic pelvic nerves using a constant voltage stimulator (Screener 3625), intravesical pressure increase was measured manometrically. The results were related to the postoperative residual urine volume, requirement of recatheterization and long-term catheterization, just as to the results of the validated International Prostatic Symptom Scores and the Quality of Life I…
Disrupting SMA activity modulates explicit and implicit emotional responses: an rTMS study.
2014
Supplementary Motor Area (SMA) has been considered as an interface between the emotional/motivational system and motor effector system. Here, we investigated whether it is possible to modulate emotional responses using non-invasive brain stimulation of the SMA. 1Hz repetitive transcranial magnetic stimulation (rTMS) trains were applied over the SMA of healthy subjects performing a task requiring to judge the valence and arousal of emotional stimuli. rTMS trains over the SMA increased the perceived valence of emotionally negative visual stimuli, while decreasing the perceived valence of emotionally positive ones. The modulatory effect on emotional valence was specific for stimuli with emotio…
Studies on the mechanism of mineralocorticoid-induced blood pressure increase in man.
1979
1. To gain insight into the mechanism of mineralocorticoid-induced blood pressure rise in man we performed haemodynamic studies in six normotensive volunteer subjects before and during administration of the synthetic steroid 9α-fluorocortisol (0·8 mg daily) for a period of 6 weeks. In a further study, performed in seven subjects, plasma noradrenaline concentration and reactivity to exogenous noradrenaline were determined before and during administration of the mineralocorticoid. 2. Within the first week of steroid administration an increase in mean arterial blood pressure could be demonstrated, which was due to an increase in cardiac output. After the sixth week the elevated blood pressure …
Sympathetic nervous activity and the pressor effect of noradrenaline under chronic?-?-adrenoceptor blockade with labetalol in hypertension
1983
In 14 patients with essential hypertension, the influence of the alpha- and beta-adrenoceptor blocking drug labetalol on blood pressure, heart rate, plasma renin, plasma noradrenaline and pressor effect of exogenous noradrenaline was investigated during long-term treatment. During the initial four weeks of treatment, labetalol at a dose of 400 mg/day showed a slight effect only on supine blood pressure, whereas upright blood pressure was already lowered effectively after the second week of treatment (p less than 0.01). An increase in the mean dose to 850 mg/day had an additional blood pressure-lowering effect (p less than 0.001), whereby a preferential decrease of the orthostatic blood pres…