Human Dorsal Root Ganglion Stimulation Reduces Sympathetic Outflow and Long-Term Blood Pressure.

This study hypothesized that dorsal root ganglion (DRG) stimulation would reduce sympathetic nerve activity and would alter hemodynamic variables. This study directly recorded muscle sympathetic nerve activity during ON and OFF stimulation of the DRG while measuring hemodynamic parameters. DRG stimulation significantly reduced the firing frequency of sympathetic nerves, as well as significantly reducing blood pressure, with greater reductions evident when stimulation was left-sided. Left-sided DRG stimulation lowers sympathetic nerve activity, leading to long-term phenotypic changes. This raises the potential of DRG stimulation being used to treat de novo autonomic disorders such as hypertension or heart failure.

High-Intensity Interval Training Decreases Muscle Sympathetic Nerve Activity in Men With Essential Hypertension and in Normotensive Controls.

Exercise training is a cornerstone in reducing blood pressure (BP) and muscle sympathetic nerve activity (MSNA) in individuals with essential hypertension. High-intensity interval training (HIIT) has been shown to be a time efficient alternative to classical continuous training in lowering BP in essential hypertension, but the effect of HIIT on MSNA levels has never been investigated. Leg MSNA responsiveness to 6 weeks of HIIT was examined in 14 hypertensive men (HYP; age: 62 ± 7 years, night time BP: 136 ± 12/83 ± 8 mmHg, BMI: 28 ± 3 kg/m2), and 10 age-matched normotensive controls (NORM; age: 60 ± 8 years, night time BP: 116 ± 2/68 ± 4 mmHg and BMI: 27 ± 3 kg/m2). Before training, MSNA levels were not different between HYP and NORM (burst frequency (BF): 41.0 ± 10.3 vs. 33.6 ± 10.6 bursts/min and burst incidence (BI): 67.5 ± 19.7 vs. 64.2 ± 17.0 bursts/100 heart beats, respectively). BF decreased (P < 0.05) with training by 13 and 5% in HYP and NORM, respectively, whereas BI decreased by 7% in NORM only, with no difference between groups. Training lowered (P < 0.05) night-time mean arterial- and diastolic BP in HYP only (100 ± 8 vs. 97 ± 5, and 82 ± 6 vs. 79 ± 5 mmHg, respectively). The change in HYP was greater (P < 0.05) compared to NORM. Training reduced (P < 0.05) body mass, visceral fat mass, and fat percentage similarly within- and between groups, with no change in fat free mass. Training increased (P < 0.05) V̇O2-max in NORM only. Six weeks of HIIT lowered resting MSNA levels in age-matched hyper- and normotensive men, which was paralleled by a significant reduction in BP in the hypertensive men.

Variations in Cardiovascular Structure, Function, and Geometry in Midlife Associated With a History of Hypertensive Pregnancy.

Hypertensive pregnancy is associated with increased maternal cardiovascular risk in later life. A range of cardiovascular adaptations after pregnancy have been reported to partly explain this risk. We used multimodality imaging to identify whether, by midlife, any pregnancy-associated phenotypes were still identifiable and to what extent they could be explained by blood pressure. Participants were identified by review of hospital maternity records 5 to 10 years after pregnancy and invited to a single visit for detailed cardiovascular imaging phenotyping. One hundred seventy-three women (age, 42±5 years, 70 after normotensive and 103 after hypertensive pregnancy) underwent magnetic resonance imaging of the heart and aorta, echocardiography, and vascular assessment, including capillaroscopy. Women with a history of hypertensive pregnancy had a distinct cardiac geometry with higher left ventricular mass index (49.9±7.1 versus 46.0±6.5 g/m2; P=0.001) and ejection fraction (65.6±5.4% versus 63.7±4.3%; P=0.03) but lower global longitudinal strain (-18.31±4.46% versus -19.94±3.59%; P=0.02). Left atrial volume index was also increased (40.4±9.2 versus 37.3±7.3 mL/m2; P=0.03) and E:A reduced (1.34±0.35 versus 1.52±0.45; P=0.003). Aortic compliance (0.240±0.053 versus 0.258±0.063; P=0.046) and functional capillary density (105.4±23.0 versus 115.2±20.9 capillaries/mm2; P=0.01) were reduced. Only differences in functional capillary density, left ventricular mass, and atrial volume indices remained after adjustment for blood pressure (P<0.01, P=0.01, and P=0.04, respectively). Differences in cardiac structure and geometry, as well as microvascular rarefaction, are evident in midlife after a hypertensive pregnancy, independent of blood pressure. To what extent these phenotypic patterns contribute to cardiovascular disease progression or provide additional measures to improve risk stratification requires further study.

A single-centre investigator-blinded randomised parallel-group study protocol to investigate the influence of an acclimatisation appointment on children's behaviour during N2O/O2 sedation as measured by psychological, behavioural and real-time physiological parameters.

AIMS AND OBJECTIVES: To describe a study protocol of a randomised control trial (RCT) assessing the effectiveness, in reducing dental anxiety, of an acclimatising nitrous oxide sedation (N2O) session prior to actual dental treatment with N2O. MATERIALS AND METHODS: A single-centre investigator-blinded parallel-group RCT conducted in a postgraduate dental hospital in Dubai, United Arab Emirates (UAE). Anxious children requiring N2O (aged 5-15 years) will be randomly assigned to; a study group: children who will have a preparatory N2O trial experience or; a control group: children who will only have N2O explained to them. Treatment with N2O for both groups will start at the second visit. The following outcomes will be recorded: completion of dental treatment, anxiety scores at baseline and after treatment (using the Modified Child Dental Anxiety Scale faces), behaviour of the child (using Frankl Rating Behaviour Scale) and the acquisition of real-time physiological anxiety-related parameters (using E4® electronic wrist devices). RESULTS: The data will be analysed statistically. DISCUSSION: There is a paucity of research regarding dental N2O acclimatising appointments. This RCT will supplement existing literature. CONCLUSIONS: This RCT will report whether prior acclimatising of a child to N2O sedation is effective, or not, in improving dental treatment behaviour.

Regional Cerebral Activation Accompanies Sympathoexcitation in Women With Polycystic Ovary Syndrome.

CONTEXT: Polycystic ovary syndrome (PCOS) is associated with increased sympathetic nervous system activation, but the cerebral pathways involved are unclear. OBJECTIVE: To compare cerebral [blood oxygen level-dependent (BOLD) functional MRI], pressor [blood pressure (BP), heart rate (HR], and muscle sympathetic nerve activity (MSNA) responses to isometric forearm contraction (IFC) in women with PCOS and matched control subjects. DESIGN: Case-control study. SETTING: Referral center. PARTICIPANTS: Patients with PCOS (n = 20; mean ± SD data: age, 29.8 ± 4.8 years; body mass index (BMI), 26.1 ± 4.9 kg/ m2) and 20 age- and BMI-matched control subjects (age, 29.7 ± 5.0 years; BMI, 26.1 ± 4.8 kg/ m2). MAIN OUTCOME MEASURES: BP, HR, catecholamine, and MSNA responses to 30% IFC. BOLD signal change was modeled for BP response to 30% IFC. RESULTS: Although HR and BP increased to a similar extent in both groups after IFC, MSNA burst frequency increased by 68% in the PCOS group compared with 11.9% in control subjects (n = 7 in both groups; P = 0.002). Brain activation indexed by the BOLD signal in response to IFC was significantly greater in the PCOS group (n = 15) compared with controls (n = 15) in the right orbitofrontal cortex (P < 0.0001). Adjustment for insulin sensitivity, but not hyperandrogenism, abolished these between-group differences. CONCLUSION: Our study confirms enhanced sympathoexcitation in women with PCOS and demonstrates increased regional brain activation in response to IFC. The right orbitofrontal cortex BOLD signal change in women with PCOS is associated with insulin sensitivity. Additional studies are warranted to clarify whether this may offer a novel target for cardiovascular risk reduction.

Neonatal autonomic function after pregnancy complications and early cardiovascular development.

BACKGROUND: Heart rate variability (HRV) has emerged as a predictor of later cardiac risk. This study tested whether pregnancy complications that may have long-term offspring cardiac sequelae are associated with differences in HRV at birth, and whether these HRV differences identify abnormal cardiovascular development in the postnatal period. METHODS: Ninety-eight sleeping neonates had 5-min electrocardiogram recordings at birth. Standard time and frequency domain parameters were calculated and related to cardiovascular measures at birth and 3 months of age. RESULTS: Increasing prematurity, but not maternal hypertension or growth restriction, was associated with decreased HRV at birth, as demonstrated by a lower root mean square of the difference between adjacent NN intervals (rMSSD) and low (LF) and high-frequency power (HF), with decreasing gestational age (p < 0.001, p = 0.009 and p = 0.007, respectively). We also demonstrated a relative imbalance between sympathetic and parasympathetic tone, compared to the term infants. However, differences in autonomic function did not predict cardiovascular measures at either time point. CONCLUSIONS: Altered cardiac autonomic function at birth relates to prematurity rather than other pregnancy complications and does not predict cardiovascular developmental patterns during the first 3 months post birth. Long-term studies will be needed to understand the relevance to cardiovascular risk.

Long-term cerebral white and gray matter changes after preeclampsia.

OBJECTIVE: To determine whether changes in cerebral structure are present after preeclampsia that may explain increased cerebrovascular risk in these women. METHODS: We conducted a case control study in women between 5 and 15 years after either a preeclamptic or normotensive pregnancy. Brain MRI was performed. Analysis of white matter structure was undertaken using voxel-based segmentation of fluid-attenuation inversion recovery sequences to assess white matter lesion volume and diffusion tensor imaging to measure microstructural integrity. Voxel-based analysis of gray matter volumes was performed with adjustment for skull size. RESULTS: Thirty-four previously preeclamptic women (aged 42.8 ± 5.1 years) and 49 controls were included. Previously preeclamptic women had reduced cortical gray matter volume (523.2 ± 30.1 vs 544.4 ± 44.7 mL, p < 0.05) and, although both groups displayed white matter lesions, changes were more extensive in previously preeclamptic women. They displayed increased temporal lobe white matter disease (lesion volume: 23.2 ± 24.9 vs 10.9 ± 15.0 µL, p < 0.05) and altered microstructural integrity (radial diffusivity: 538 ± 19 vs 526 ± 18 × 10-6 mm2/s, p < 0.01), which also extended to occipital and parietal lobes. The degree of temporal lobe white matter change in previously preeclamptic women was independent of their current cardiovascular risk profile (p < 0.05) and increased with time from index pregnancy (p < 0.05). CONCLUSION: A history of preeclampsia is associated with temporal lobe white matter changes and reduced cortical volume in young women, which is out of proportion to their classic cardiovascular risk profile. The severity of changes is proportional to time since pregnancy, which would be consistent with continued accumulation of damage after pregnancy.

Differentiated baroreflex modulation of sympathetic nerve activity during deep brain stimulation in humans.

Targeted electric deep brain stimulation in midbrain nuclei in humans alters cardiovascular parameters, presumably by modulating autonomic and baroreflex function. Baroreflex modulation of sympathetic outflow is crucial for cardiovascular regulation and is hypothesized to occur at 2 distinct brain locations. The aim of this study was to evaluate sympathetic outflow in humans with deep brain stimulating electrodes during ON and OFF stimulation of specific midbrain nuclei known to regulate cardiovascular function. Multiunit muscle sympathetic nerve activity was recorded in 17 patients undergoing deep brain stimulation for treatment of chronic neuropathic pain (n=7) and Parkinson disease (n=10). Sympathetic outflow was recorded during ON and OFF stimulation. Arterial blood pressure, heart rate, and respiratory frequency were monitored during the recording session, and spontaneous vasomotor and cardiac baroreflex sensitivity were assessed. Head-up tilt testing was performed separately in the patients with Parkinson disease postoperatively. Stimulation of the dorsal most part of the subthalamic nucleus and ventrolateral periaqueductal gray resulted in improved vasomotor baroreflex sensitivity, decreased burst frequency and blood pressure, unchanged burst amplitude distribution, and a reduced fall in blood pressure after tilt. Stimulation of the dorsolateral periaqueductal gray resulted in a shift in burst amplitude distribution toward larger amplitudes, decreased spontaneous beat-to-beat blood pressure variability, and unchanged burst frequency, baroreflex sensitivity, and blood pressure. Our results indicate that a differentiated regulation of sympathetic outflow occurs in the subthalamic nucleus and periaqueductal gray. These results may have implications in our understanding of abnormal sympathetic discharge in cardiovascular disease and provide an opportunity for therapeutic targeting.

Stress-induced cardiomyopathy in Sweden: evidence for different ethnic predisposition and altered cardio-circulatory status.

BACKGROUND: In this paper, we report about new insights regarding clinical course, long-term outcome, ethnic/genetic predisposition and cardio-circulatory status in the large stress-induced cardiomyopathy (SIC) cohort from Sweden. METHODS AND RESULTS: We have included 115 consecutive SIC patients between January 2005 and January 2010 at Sahlgrenska University Hospital in Gothenburg. Hemodynamic status and sympathetic nerve activity were evaluated and compared with those of healthy controls. Mean age was 64, and 14% were males. Thirty-day and 3-year mortality was 6 and 10%, respectively. Eleven percent had ischemic heart disease, 3% developed thromboembolic complications, 6% had cardiac arrest and 14% developed cardiogenic shock. The great majority of SIC patients (93%) were ethnic Swedes. In three families, several close relatives developed SIC. Fourteen percent developed two or more episodes of SIC. Hemodynamic evaluation has shown subnormal systemic vascular resistance, 22% lower sympathetic activity and preserved cardiac output in SIC patients. CONCLUSIONS: SIC affects both men and women of different ages and is associated with significant short- and long-term mortality. There is a strong signal for the presence of ethnic/genetic predisposition to develop SIC. Sympathetic activity and systemic vascular resistance are lower in SIC patients, suggesting that SIC is a cardio-circulatory phenomenon.

Sympathetic nerve activity in women 40 years after a hypertensive pregnancy.

OBJECTIVES: Epidemiological studies show that women with pregnancies complicated by hypertension have an increased risk of cardiovascular morbidity later in life. The underlying mechanisms to the risk increase remain largely unknown. This study evaluated sympathetic nerve activity in women with hypertensive pregnancies 40 years earlier compared to women with normotensive pregnancies. We hypothesized that sympathetic outflow would be increased in women with previous hypertensive pregnancies and that this partly may explain the increased cardiovascular risk. METHODS: Sympathetic nerve activity to the muscle vascular bed [muscle sympathetic nerve activity (MSNA)] was recorded in 28 women, 18 with and 10 without a hypertensive manifestation during pregnancy. Women were also examined with ambulatory blood pressure measurements, pulse wave velocity, blood pressure response during Stroop test and laboratory analysis. RESULTS: Women with previous hypertensive pregnancies did not show an increased sympathetic outflow compared to women with normotensive pregnancies. In eight women with treated hypertension sympathetic outflow was increased compared to normotensive women despite similar ambulatory blood pressure values (P < 0.05). During Stroop test the hypertensive women showed increased systolic blood pressure and also displayed the highest augmentation index compared to normotensive women (P < 0.05). CONCLUSION: Hypertensive pregnancies per se were not associated with increased sympathetic outflow 40 years later. The increased cardiovascular risk in women with previous hypertensive pregnancies cannot be explained by chronic activation of the sympathetic nervous system.In women with previous hypertensive pregnancies, still hypertensive though well controlled, sympathetic outflow and arterial stiffness were, however, increased compared to normotensive counterparts.

Sympathetic nerve activity in stress-induced cardiomyopathy.

PURPOSE: To evaluate directly recorded efferent sympathetic nerve traffic in patients with stress-induced cardiomyopathy (SIC). BACKGROUND: SIC is a syndrome affecting mostly postmenopausal women following severe emotional stress. Though the precise pathophysiology is not well understood, a catecholamine overstimulation of the myocardium is thought to underlie the pathogenesis. METHODS: Direct recordings of multiunit efferent postganglionic muscle sympathetic nerve activity (MSNA) were obtained from 12 female patients, 5 in the acute (24-48 h) and 7 in the recovery phase (1-6 months), with apical ballooning pattern and 12 healthy matched controls. MSNA was expressed as burst frequency (BF), burst incidence (BI) and relative median burst amplitude (RMBA %). One of the twelve patients in this study was on beta blockade treatment due to a different illness, at time of onset of SIC. All patients were investigated with ongoing medication. RESULTS: MSNA was lower in patients with SIC as compared to matched controls, but did not differ between the acute and recovery phase of SIC. RMBA %, blood pressure and heart rate did not differ between the groups. CONCLUSION: MSNA is shown to be lower in patients with SIC compared to healthy controls, suggesting that sympathetic neuronal outflow is rapidly reduced following the initial phase of SIC. A distension of the ventricular myocardium, due to excessive catecholamine release over the heart in the acute phase, may increase the firing rate of unmyelinated cardiac c-fibre afferents resulting in widespread sympathetic inhibition. Such a mechanism may underlie the lower MSNA reported in our patients.

Sex steroids, insulin sensitivity and sympathetic nerve activity in relation to affective symptoms in women with polycystic ovary syndrome.

CONTEXT: Affective symptoms are poorly understood in polycystic ovary syndrome (PCOS). Clinical signs of hyperandrogenism and high serum androgens are key features in PCOS, and women with PCOS are more likely to be overweight or obese, as well as insulin resistant. Further, PCOS is associated with high sympathetic nerve activity. OBJECTIVE: To elucidate if self-reported hirsutism, body mass index (BMI) and waistline, circulating sex steroids, sex hormone-binding globulin (SHBG), insulin sensitivity and sympathetic nerve activity are associated with depression and anxiety-related symptoms in women with PCOS. DESIGN AND METHODS: Seventy-two women with PCOS, aged 21-37 years, were recruited from the community. Hirsutism was self-reported using the Ferriman-Gallway score. Serum estrogens, sex steroid precursors, androgens and glucuronidated androgen metabolites were analyzed by gas and liquid chromatography/mass spectroscopy (GC-MS/LC-MS/MS) and SHBG by chemiluminiscent microparticle immunoassay (CMIA). Insulin sensitivity was measured with euglycemic hyperinsulinemic clamp. Sympathetic nerve activity was measured with microneurography. Symptoms of depression and anxiety were self-reported using the Montgomery Åsberg Depression Rating Scale (MADRS-S) and the Brief Scale for Anxiety (BSA-S). RESULTS: Circulating concentrations of testosterone (T) (P=0.026), free T (FT) (P=0.025), and androstane-3α 17ß-diol-3glucuronide (3G) (P=0.029) were lower in women with depression symptoms of potential clinical relevance (MADR-S≥11). The odds of having a MADRS-S score ≥11 were higher with lower FT and 3G. No associations with BSA-S were noted. CONCLUSION: Lower circulating FT and 3G were associated with worse self-reported depression symptoms. The relationship between mental health, sex steroids and corresponding metabolites in PCOS requires further investigation.

Muscle sympathetic nerve activity is related to a surrogate marker of endothelial function in healthy individuals.

BACKGROUND: Evidence from animal studies indicates the importance of an interaction between the sympathetic nervous system and the endothelium for cardiovascular regulation. However the interaction between these two systems remains largely unexplored in humans. The aim of this study was to investigate whether directly recorded sympathetic vasoconstrictor outflow is related to a surrogate marker of endothelial function in healthy individuals. METHODS AND RESULTS: In 10 healthy normotensive subjects (3 f/7 m), (age 37+/-11 yrs), (BMI 24+/-3 kg/m(2)) direct recordings of sympathetic action potentials to the muscle vascular bed (MSNA) were performed and endothelial function estimated with the Reactive Hyperaemia- Peripheral Arterial Tonometry (RH-PAT) technique. Blood samples were taken and time spent on leisure-time physical activities was estimated. In all subjects the rate between resting flow and the maximum flow, the Reactive Hyperemic index (RH-PAT index), was within the normal range (1.9-3.3) and MSNA was as expected for age and gender (13-44 burst/minute). RH-PAT index was inversely related to MSNA (r = -0.8, p = 0.005). RH-PAT index and MSNA were reciprocally related to time (h/week) spent on physical activity (p = 0.005 and p = 0.006 respectively) and platelet concentration (PLT) (p = 0.02 and p = 0.004 respectively). CONCLUSIONS: Our results show that sympathetic nerve activity is related to a surrogate marker of endothelial function in healthy normotensive individuals, indicating that sympathetic outflow may be modulated by changes in endothelial function. In this study time spent on physical activity is identified as a predictor of sympathetic nerve activity and endothelial function in a group of healthy individuals. The results are of importance in understanding mechanisms underlying sympathetic activation in conditions associated with endothelial dysfunction and emphasise the importance of a daily exercise routine for maintenance of cardiovascular health.

Firing probability and mean firing rates of human muscle vasoconstrictor neurones are elevated during chronic asphyxia.

Elevated muscle sympathetic nerve activity (MSNA) features in many cardiovascular diseases, but how this sympathoexcitation is brought about differs across pathologies. Unitary recordings from post-ganglionic muscle vasoconstrictor neurones in human subjects have shown that the augmented MSNA in the obstructive sleep apnoea syndrome (OSAS) is associated with an increase in firing probability and mean firing rate, and an increase in multiple within-burst firing. Here we characterize the firing properties of muscle vasoconstrictor neurones in patients with chronic obstructive pulmonary disease (COPD), who are chronically asphyxic. We tested the hypothesis that this elevated chemical drive would shift the firing pattern from that seen in healthy subjects to that seen in OSAS. The mean firing probability (52%) and mean firing rate (0.92 Hz) of 17 muscle vasoconstrictor neurones recorded in COPD were comparable to those previously recorded in OSAS (51% and 0.96 Hz), but significantly higher than those recorded in a group of healthy subjects with high levels of resting MSNA (35% and 0.33 Hz). In COPD single neurones fired once in 63% of cardiac intervals, comparable to OSAS (59%), but significantly lower than in the healthy group (78%). Conversely, single neurones fired twice in 25% of cardiac intervals, similar to OSAS (27%), but significantly higher than in the healthy group (18%). We conclude that the chronic asphyxia associated with COPD results in an increase in the firing probability and mean firing frequency of muscle vasoconstrictor neurones and causes a shift towards multiple firing, reflecting an increase in central muscle vasoconstrictor drive.

Low-frequency electroacupuncture and physical exercise decrease high muscle sympathetic nerve activity in polycystic ovary syndrome.

We have recently shown that polycystic ovary syndrome (PCOS) is associated with high muscle sympathetic nerve activity (MSNA). Animal studies support the concept that low-frequency electroacupuncture (EA) and physical exercise, via stimulation of ergoreceptors and somatic afferents in the muscles, may modulate the activity of the sympathetic nervous system. The aim of the present study was to investigate the effect of these interventions on sympathetic nerve activity in women with PCOS. In a randomized controlled trial, 20 women with PCOS were randomly allocated to one of three groups: low-frequency EA (n = 9), physical exercise (n = 5), or untreated control (n = 6) during 16 wk. Direct recordings of multiunit efferent postganglionic MSNA in a muscle fascicle of the peroneal nerve before and following 16 wk of treatment. Biometric, hemodynamic, endocrine, and metabolic parameters were measured. Low-frequency EA (P = 0.036) and physical exercise (P = 0.030) decreased MSNA burst frequency compared with the untreated control group. The low-frequency EA group reduced sagittal diameter (P = 0.001), while the physical exercise group reduced body weight (P = 0.004) and body mass index (P = 0.004) compared with the untreated control group. Sagittal diameter was related to MSNA burst frequency (Rs = 0.58, P < 0.005) in the EA group. No correlation was found for body mass index and MSNA in the exercise group. There were no differences between the groups in hemodynamic, endocrine, and metabolic variables. For the first time we demonstrate that low-frequency EA and physical exercise lowers high sympathetic nerve activity in women with PCOS. Thus, treatment with low-frequency EA or physical exercise with the aim to reduce MSNA may be of importance for women with PCOS.

Firing properties of sudomotor neurones in hyperhidrosis and thermal sweating.

OBJECTIVES: Idiopathic palmar-plantar hyperhidrosis is characterized by excessive sweating of the palms and feet, and is commonly treated by transthoracic regional sympathicotomy. As the condition is believed to be due to a high sudomotor drive, we wanted to assess the firing properties of individual sudomotor neurones in this state of sympathoexcitation, extending our recent work on other pathologies associated with high sympathetic nerve activity. METHODS: Single-unit recordings were made from eight sudomotor neurones supplying the fingers via tungsten microelectrodes inserted percutaneously into the median nerve at the wrist or upper arm. RESULTS: Typical of sudomotor, muscle vasoconstrictor and cutaneous vasoconstrictor neurones recorded in healthy individuals in states of high sympathetic drive, all units had low firing probabilities (active in only 30.0 +/- 6.7 (SE) % of cardiac intervals) and primarily fired only once per heart beat. The percentage of cardiac intervals in which the neurones generated 1, 2, 3 or 4 spikes was 60.4 +/- 6.3, 22.9 +/- 3.9, 9.7 +/- 2.1 and 3.4 +/- 1.3%, respectively. For comparison, these values were 77.6 +/- 7.7, 15.0 +/- 4.1, 4.6 +/- 2.3 and 1.8 +/- 1.3% for eight sudomotor neurones innervating the hairy skin of the foot during thermally-induced sweating in normal subjects. INTERPRETATION: We conclude that the firing properties of spontaneously active sudomotor neurones in subjects with hyperhidrosis are similar to those of sudomotor neurones active during thermal sweating, reflecting an increase in central sympathetic drive to the sweat glands in hyperhidrosis.

Is polycystic ovary syndrome associated with high sympathetic nerve activity and size at birth?

Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disturbance among women of reproductive age and is proposed to be linked with size at birth and increased prevalence of cardiovascular disease. A disturbance in the sympathetic nervous system may contribute to the etiology of PCOS. This study evaluates sympathetic outflow in PCOS and its relation to size at birth. Directly recorded sympathetic nerve activity to the muscle vascular bed (MSNA) was obtained in 20 women with PCOS and in 18 matched controls. Ovarian ultrasonographic evaluation, biometric, hormonal, and biochemical parameters were measured, and birth data were collected. Women with PCOS had increased MSNA (30 +/- 8 vs. 20 +/- 7 burst frequency, P < 0.0005) compared with controls. MSNA was positively related to testosterone (r = 0.63, P < 0.005) and cholesterol (r = 0.55, P = 0.01) levels in PCOS, which, in turn, were not related to each other. Testosterone level was a stronger predictor of MSNA than cholesterol. Birth size did not differ between the study groups. This is the first study to directly address sympathetic nerve activity in women with PCOS and shows that PCOS is associated with high MSNA. Testosterone and cholesterol levels are identified as independent predictors of MSNA in PCOS, although testosterone has a stronger impact. The increased MSNA in PCOS may contribute to the increased cardiovascular risk and etiology of the condition. In this study, PCOS was not related to size at birth.

Epidermal growth factor levels are related to diastolic blood pressure and carotid artery stiffness.

OBJECTIVES: The epidermal growth factor (EGF) is believed to be involved in vascular remodelling. EGF receptors are expressed in human atherosclerotic tissue. DESIGN: In order to study the role of EGF in vascular remodelling and early progression of atherosclerosis, 17 men and 16 women aged 20 to 45 years were recruited. Common Carotid Artery Stiffness index (CCA SI) and blood pressure were evaluated. In addition, serum levels of EGF and blood lipids were measured. RESULTS: The levels of serum EGF were significantly correlated to diastolic blood pressure (p<0.05) and CCA SI (p<0.05). Subjects with EGF concentrations in the upper median had significantly lower levels of HDL (High Density Lipoproteins) (p<0.05) and ApoA1 (Apolipoprotein) (p<0.05) than those with EGF concentrations in the lower median. DISCUSSION: High serum level of EGF is associated with elevated diastolic blood pressure and increased vessel stiffness suggesting a possible functional role of EGF in the cardiovascular system in a healthy population.