Index Of Sympathetic Activity Research Articles

Effects of central sympathetic activation on repolarization-dispersion during short-term myocardial ischemia in anesthetized rats.

Sympathetic activation during myocardial ischemia enhances arrhythmogenesis, but the underlying pathophysiologic mechanisms remain unclear. We investigated the central sympathetic effects on ventricular repolarization during the early-period post-coronary artery occlusion. We studied 12 Wistar rats (254±2 g) for 30 min following left coronary artery ligation, with (n=6) or without (n=6) pretreatment with the central sympatholytic agent clonidine. Mapping of left and right ventricular epicardial electrograms was performed with a 32-electrode array. As an index of sympathetic activation, heart rate variability in the frequency domain was calculated. Heart rate and repolarization duration were measured with a custom-made recording and analysis software, followed by calculation of intra- and inter-ventricular dispersion of repolarization. Heart rate and heart rate variability indicated lower sympathetic activation in clonidine-treated rats during ischemia. Repolarization duration in the left ventricle prolonged after clonidine at baseline, independently of heart rate, but no differences were present 30 min post-ligation. Dispersion of repolarization in the right ventricle remained stable during ischemia, whereas it increased in the left ventricle, equally in both groups. A similar trend was observed for inter-ventricular dispersion, without differences between groups. In addition to intra-ventricular repolarization-dispersion, anterior-wall myocardial ischemia may also increase inter-ventricular repolarization-dispersion. Progressive central sympathetic activation occurs during myocardial ischemia, but it does not affect intra- or inter-ventricular dispersion of ventricular repolarization during the early phase. Further research is warranted on the potential effects during subsequent time-periods.

Effect of 100 Hz electroacupuncture on salivary immunoglobulin A and the autonomic nervous system.

BackgroundA previous study has reported that low-frequency (LF) electroacupuncture (EA) influences salivary secretory immunoglobulin A (sIgA) and the autonomic nervous system (ANS). The ANS is known to control the secretion volume of sIgA; however, the effect of high-frequency (HF) EA on salivary sIgA has not been determined. We investigated whether HF EA affects salivary sIgA levels and the ANS.MethodSixteen healthy subjects were randomly classified into two groups: a control group and an EA group. After a 5 min rest, subjects in the EA group received EA at 100 Hz bilaterally at LI4 and LI11 for 15 min before resting for a further 40 min post-stimulation. Subjects in the control group rested for a total of 60 min. Measurements of the ANS and sIgA levels in both groups were made before, immediately after, 20 min after, and 40 min after rest or 15 min EA treatment. HF and LF components of heart rate variability were analysed as markers of ANS function. LF/HF ratio and HF were taken as indices of sympathetic and parasympathetic nerve activity, respectively. Salivary protein concentrations and sIgA levels were determined by Bradford protein assay and ELISA, respectively.ResultsLF/HF ratio was significantly increased immediately after EA. HF was significantly increased at 20 min after EA and sIgA level was significantly increased at 40 min after EA. In addition, HF and salivary sIgA level were positively correlated with each another.ConclusionsHF EA exerted sequential positive effects on sympathetic nerve activity, parasympathetic nerve activity, and salivary sIgA level (immediately and after 20 and 40 min, respectively). HF EA may increase salivary sIgA levels by influencing parasympathetic nerve activity.

Autonomic nervous system in children with autism spectrum disorder

Background. Autism spectrum disorder (ASD) is a neurodevelopmental disorder of unknown etiology, defined by impaired social communication and interaction, and by the presence of restrictive and repetitive behaviour. The autonomic imbalance, in which one branch of the autonomic nervous system (ANS) dominates over the other, is associated with a lack of dynamic flexibility and adaptability. The aim of this article was to summarize the current state of knowledge regarding ANS activity in children with ASD. Methods and Results. We have collected the latest information on autism and ANS regulation from available medical resources (PubMed). We focused on two main physiological parameters such as heart rate variability (HRV) and electrodermal activity (EDA) as the noninvasive indices of vagal and sympathetic activity, respectively. The studies showed atypical autonomic activity at rest as well as in response to stress. Conclusion. ASD symptoms are associated with pervasive abnormalities in the central nervous system including structures and networks involved in the complex ANS regulation. Importantly, the autonomic imbalance in a manner of higher sympathetic activity associated with lower vagal activity is associated with increased risk of cardiovascular, and other adverse outcomes in ASD. Therefore, we suggest that detailed complex analysis of physiological parameters may illuminate the pathway linking ASD and autonomic nervous system activity.

A Triphasic Change of Cardiac Autonomic Nervous System During Electroconvulsive Therapy.

Dynamic autonomic activity changes have been repeatedly reported during electroconvulsive therapy (ECT). However, the specific timing of these changes remains unclear. To clarify whether sympathetic or parasympathetic nervous activity contributes separately to the second stage and the third stage during and after induced seizures by ECT, we examined heart rate (HR) and spectral analysis of variability (HRV) during ECT. Seventeen patients with depression participated in the study and underwent ECT. The R-R intervals (RRI) were recorded and analyzed sequentially for the HRV indices high-frequency (HF) (an index of parasympathetic activity) and low-frequency (LF)/high-frequency (an index of sympathetic activity) for 4 minutes before and after stimulus onset by the maximum entropy method. Averaged HRs were compared between 3 heart beats prestimulus and poststimulus onset. The HRV power in the range of 30 to 80 and 80 to 130 seconds after a seizure was compared between the HF and LF/HF components. There was a significant reduction of the averaged HR over 3 HRs just after stimulus onset, suggesting parasympathetic dominance in the first phase. The LF/HF power significantly increased in the 30 to 80 s range after stimulus onset, whereas the HF power significantly increased in the 80 to 130 s range after stimulus onset, reflecting sympathetic activation in the second phase and parasympathetic activation in the third phase, respectively. The evaluation of HR and HRV revealed a triphasic change from parasympathetic to sympathetic to parasympathetic cardiac autonomic activity after ECT stimulus onset in depression patients.

Central integration and neural control of blood pressure during the cold pressor test: a comparison between hydrochlorothiazide and aliskiren.

Individuals with hypertension and sympathetic overactivity are at risk for cardiovascular events. Renin inhibitors are new while thiazide diuretics are first-class drugs used for treatment of hypertension. The purpose of this study was to determine whether 6 months of treatment with aliskiren (ALSK) or hydrochlorothiazide (HCTZ) would alter blood pressure (BP) and muscle sympathetic nerve activity (MSNA) indices in older mild hypertensives during a cold pressor test (CPT). We hypothesized that the ALSK group would demonstrate a blunted response compared to HCTZ. Nineteen (9 men, 10 women) subjects performed a CPT pre- and post treatment where heart rate (HR), systolic BP (SBP) and diastolic BP (DBP), and MSNA were measured. Blood samples were withdrawn for assessment of renal-adrenal hormones. Both medications lowered ambulatory SBP and DBP (P < 0.05). Direct renin tended to be higher in the ALSK group after treatment (P = 0.081). Aldosterone was higher in the HCTZ group after treatment (P < 0.001). As expected, both groups showed increases in HR, SBP, DBP, and MSNA during the CPT (all P < 0.05). All cardiovascular and MSNA responses were similar pre- and post treatment in both groups (peak CPT SBP: 26 ± 10 vs. 17 ± 21 and 21 ± 20 vs. 29 ± 15 mmHg for pre vs. post for HCTZ and ALSK, respectively; peak CPT MSNA burst frequency: 13 ± 8 vs. 11 ± 11 and 11 ± 17 vs. 6 ± 13 bursts/min; all P > 0.05). Treatment with these antihypertensive medications lowered BP but was not successful in lowering the responsiveness to the CPT.

Sex differences and blood pressure regulation in humans.

What is the topic of this review? Over the past decade, our team has investigated interindividual variability in human blood pressure regulation. What advances does it highlight? In men, we have found a tight relationship between indices of sympathetic activity and vascular resistance across the age span. This relationship is absent in young women but seen in postmenopausal women. These sex and age differences in vascular resistance are largely a result of changes in the balance of vasodilating and vasoconstricting adrenergic receptor tone. When these changes are considered along with cardiac output, a coherent picture is beginning to emerge of why blood pressure rises more with age in women than men. Arterial pressure is a key regulated variable in the cardiovascular system with important health implications. Over the last 12 years, we have used physiological measurements, including muscle sympathetic nerve activity (MSNA), to explore the balance among mean arterial blood pressure, cardiac output and total peripheral resistance (TPR) in normotensive humans. We have shown that these determinants of blood pressure can vary widely in different subjects and how they vary depends on sex and age. In young men, there is a direct relationship between MSNA and TPR but no relationship with blood pressure. This is because cardiac output is proportionally lower in those with high MSNA and TPR. In contrast, in young women there is no relationship between MSNA and TPR (or cardiac output); this is because β-adrenergic vasodilator mechanisms offset α-adrenergic vasoconstriction. Thus, blood pressure is unrelated to MSNA in young women. In older women, β-adrenergic vasodilator mechanisms are diminished, and a direct relationship between MSNA and TPR is seen. In older men, the relationships among these variables are less clear cut, perhaps owing to age-related alterations in endothelial function. With ageing, the relationship between MSNA and blood pressure becomes positive, more so in women than in men. The finding that the physiological control of blood pressure is so different in men and women and that it varies with age suggests that future studies of mechanisms of hypertension will reveal corresponding differences among groups.

Psychosocial Stress Increases Salivary Alpha-Amylase Activity Independently from Plasma Noradrenaline Levels.

Salivary alpha-amylase activity (sAA) and plasma noradrenaline (NA) concentrations are often considered to be surrogate markers of sympathetic activation in response to stress. However, despite accumulating evidence for a close association between sAA and noradrenaline and other indicators of sympathetic activity, reliability and generality of this relation remains unclear. We employed the Trier Social Stress Test (TSST) in order to directly compare the responses in sAA and NA to psychological stress in healthy volunteers (n = 23). The TSST significantly increased sAA and NA plasma levels with no significant differences in females and males. However, when subjects were divided according to their NA responses into low versus high responders, both groups did not significantly differ in their sAA before, during or after stress exposure. These data suggest that in response to acute psychological stress both plasma NA levels and sAA reflect sympathetic activity, however seemed to increase independently from each other.

A small randomized pilot study of a workplace mindfulness-based intervention for surgical intensive care unit personnel: effects on salivary α-amylase levels.

To determine whether a workplace stress-reduction intervention decreases reactivity to stress among personnel exposed to a highly stressful occupational environment. Personnel from a surgical intensive care unit were randomized to a stress-reduction intervention or a waitlist control group. The 8-week group mindfulness-based intervention included mindfulness, gentle yoga, and music. Psychological and biological markers of stress were measured 1 week before and 1 week after the intervention. Levels of salivary α-amylase, an index of sympathetic activation, were significantly decreased between the first and second assessments in the intervention group with no changes in the control group. There was a positive correlation between salivary α-amylase levels and burnout scores. These data suggest that this type of intervention could decrease not only reactivity to stress but also the risk of burnout.

MP89-17 DIFFERENT INJECTION NUMBER OF INTRAVESICAL ONABOTULINUMTOXINA INJECTION FOR OVERACTIVE BLADDER SYNDROME DOES NOT AFFECT TREATMENT OUTCOME - A PROSPECTIVE RANDOMIZED COMPARATIVE STUDY

(LF/HF) values as an indicator for sympathetic activity. We then retrospectively investigated the associations of these parameters regarding ANS activity; HF, LF/HF and heart rate (HR) with urinary frequency recorded in the activity logs during the 24-hour Holter ECG using Spearman’s correlation coefficient and Wilcoxon rank-sum test. RESULTS: The average numbers of urinations in all cases were 6.09 2.06 times during the daytime and 0.87 1.16 times during the nighttime. Spearman’s correlation coefficient analysis showed a significant inverse correlation between age and each of HF, LF/HF and HR. A significant correlation was found between the number of daytime urinations and HR, and between the number of nighttime urinations and LF/HF. In men, a significant correlation was noted between the number of nighttime urinations and HR, whereas in women, a significant correlation existed between the number of daytime urinations and HR, between the number of nighttime urinations and HF, and between the number of nighttime urinations and LF/HF. CONCLUSIONS: Although the present study is a retrospective review of ambulatory patients who underwent 24-hour Holter ECG, its findings suggest that there are associations between ANS activity and urinary frequency, and different outcomes were observed depending on the age and gender. However, some of the participants had such underlying diseases as hypertension and diabetes, and particularly in elderly patients, ANS activity tend to decrease relatively due to the impact of arteriosclerosis and other such conditions. Therefore, these factors must be taken into account when interpreting the findings. HR has the potential to serve as an easily measurable urinary parameter. Thus, we intend to investigate this potential in a prospective study targeting patients with LUTS.

Altered cardiovascular autonomic function in young normotensive offspring of hypertensive parents - Is obesity an additional risk factor?

A study was undertaken to analyze the nature and magnitude of autonomic dysregulation that starts early in the offspring of a hypertensive parent and also whether obesity in them add an additional risk for future hypertension. Forty normotensive subjects aged 18-25 years with at least one hypertensive parent constitute the study group. The study group was divided into obese and non-obese depending on their body mass index (non-obese with BMI 18.50-24.99 kg/m2; obese with BMI≥30 kg/m2). Twenty age-matched normotensive, without parental history subjects constitute the control group. Anthropometric parameters, heart rate, systolic and diastolic pressures were recorded. Heart rate variability indices like total power, LF, HF, LF/HF, SDNN, RMSSD, and PNN50% were studied. One-way ANOVA was used for simultaneous multiple group comparison followed by post hoc Tukey's test for groupwise comparison. The Pearson correlation coefficient was used to assess the relationship between BMI and other variables. Subjects who were obese with parental history of hypertension showed significantly higher heart rate, diastolic blood pressure, LF, LF/HF ratio and reduced total power, HF, SDNN, RMSSD, and PNN50% compared to the other groups with normal BMI. HF and all the time domain indices showed negative correlation and LF a positive correlation with BMI. In the obese offspring of hypertensive parents, HRV markers, which represent a vagal dominance were reduced substantially, and indices of sympathetic activity were increased. So obesity in a normotensive offspring of a hypertensive parent is an additional risk factor for the future development of hypertension as it further dysregulates the autonomic control of the heart.

The Sympathetic Nervous System and Tendinopathy: A Systematic Review

Tendinopathy is a clinical diagnosis of localised tendon pain often confirmed by imaging findings. The pathophysiological cause of the pain is unknown and the sympathetic nervous system (SNS) may be implicated. To review what is known regarding the role of the SNS in human tendinopathy. Published data describing sympathetic innervation or an index of sympathetic activity in human tendons were eligible for inclusion. Bibliographical databases (AMED, Biological Abstracts, CINAHL Plus, EMBASE, MEDLINE, Scopus, SPORTDiscus and Web of Science) were searched for relevant articles. Reference lists from included articles were screened for additional articles. Studies were scored with a quality assessment tool to identify potential sources of bias. Each question had an explicit decision rule to guide assessment. Nine case-control and four cross-sectional studies examined sympathetic innervation of tendons. There was evidence suggesting a lack of difference in sympathetic innervation of tendon proper between tendinopathy biopsies and healthy controls. In contrast, the paratendinous tissue showed evidence of increased sympathetic innervation in painful tendons. The most notable increase in SNS markers was seen in abnormal tenocytes from painful tendons. Data from two studies were suitable for meta-analysis. These heterogeneous studies revealed no difference in sympathetic innervation between painful and pain-free tendons. No studies recorded SNS activity in vivo. Sympathetic innervation in painful tendons depends on tissue type. Abnormal tenocytes may have increased capacity for self-production of sympathetic neurotransmitters. Future insight may be gained by measuring global in vivo sympathetic drive in tendinopathy.

Influence of viewing distance and size of tv on visual fatigue and feeling of involvement.

Using physiological and psychological measurements, we carried out experiments to investigate the influence of viewing distance and TV screen size on visual fatigue and feeling of involvement using 17-inch, 42-inch and 65-inch displays. The experiment was an ordinary viewing test with the content similar to everyday TV programs for one hour including scenery, sport, drama, etc., with commercials sandwiched in between. The number of participants was 16 (8 persons aged 21-31, and 8 persons aged 50-70) for each display size. In all, 48 participants viewed 3 display sizes. In our physiological evaluation, CFF (critical flicker fusion frequency), blink rate and a sympathetic nerve activity index were used; and in the psychological evaluation, questionnaires and interviews were employed. Our results, based on physiological and psychological measurements, suggest the opti- mum viewing distance to be around 165-220 cm, irrespective of screen size. Our evaluations, which are based on optimum viewing distance for minimal visual fatigue and a closer feeling of involvement, might therefore not agree with the currently recommended viewing distance, which is defined as 2 or 3 times the display's height.

Physiological Indicators of Pathologic Video Game Use in Adolescence

PurposePathologic video game use (PVGU) has been associated with a host of negative psychological, physical, and social outcomes during adolescence; however, little research has examined physiological predictors of such use. The purpose of the study was to examine physiological predictors of the development of PVGU across adolescence. MethodsThe article involves a 1-year longitudinal study across midadolescence. Participants were 374 adolescents and their parents from a large metropolitan area in the Northwest United States. PVGU was assessed via questionnaire, as were a number of control variables. A number of physiological indicators including respiratory sinus arrhythmia (RSA) and galvanic skin conductance (indices of parasympathetic and sympathetic nervous system activity, respectively) were measured during baseline, a cognitively stimulating task (Rubik's cube), and a family problem-solving task. ResultsLess RSA withdrawal to a cognitively simulating task was related to greater pathologic video game symptoms, but less RSA withdrawal to a family problem-solving task was associated with the presence of pathologic video game symptoms (p < .05). For girls only, galvanic skin conductance activation during the family problem solving was related to greater pathologic video game symptoms (p < .01). ConclusionsThese findings suggest that adolescents who do not find cognitive tasks stimulating physiologically have a greater severity of PVGU. Additionally, adolescents who show physiological signs of stress in a family task were more likely to have PVGU symptoms and only girls have more severe PVGU levels. This study is the first to show that physiological indicators predict PVGU over time in adolescence and has important implications regarding the prevention and treatment of PVGU in adolescence.

Altered autonomic nervous system activity in women with unexplained recurrent pregnancy loss.

Autonomic nervous system activity was studied to evaluate the physical and mental state of women with unexplained recurrent pregnancy loss (RPL). Heart rate variability (HRV) is a measure of beat-to-beat temporal changes in heart rate and provides indirect insight into autonomic nervous system tone and can be used to assess sympathetic and parasympathetic tone. We studied autonomic nervous system activity by measuring HRV in 100 women with unexplained RPL and 61 healthy female volunteers as controls. The degree of mental distress was assessed using the Kessler 6 (K6) scale. The K6 score in women with unexplained RPL was significantly higher than in control women. HRV evaluated on standard deviation of the normal-to-normal interval (SDNN) and total power was significantly lower in women with unexplained RPL compared with control women. These indices were further lower in women with unexplained RPL ≥4. On spectral analysis, high-frequency (HF) power, an index of parasympathetic nervous system activity, was significantly lower in women with unexplained RPL compared with control women, but there was no significant difference in the ratio of low-frequency (LF) power to HF power (LF/HF), an index of sympathetic nervous system activity, between the groups. The physical and mental state of women with unexplained RPL should be evaluated using HRV to offer mental support. Furthermore, study of HRV may elucidate the risk of cardiovascular diseases and the mechanisms underlying unexplained RPL.

Cardiac Sympathetic Dominance and Systemic Inflammation in COPD

Cardiac autonomic dysfunction is an independent determinant of adverse outcomes in many diseases. The available literature on the relative changes in sympathetic and parasympathetic components in chronic obstructive pulmonary disease (COPD) is equivocal, the clinical and physiological correlates are poorly defined and association with markers of systemic inflammation has not been explored. As both autonomic dysfunction and systemic inflammation may contribute to cardiovascular morbidity in COPD, we hypothesized that these may be associated. Sixty three stable patients of COPD and 36 controls underwent spirometry, estimation of diffusion capacity, six-minute walk test and measurements of serum interleukin-6 (IL-6) and high-sensitivity C-Reactive protein. Cardiac autonomic activity was evaluated by standard five-minute heart rate variability (HRV) recordings to obtain time- and frequency-domain indices and the averaged heart rate. We observed that HRV indices of overall autonomic modulation, the standard deviation of time intervals between consecutive normal beats (SDNN) and total power, were greater in patients with higher levels of indices of both parasympathetic and sympathetic activity. The heart rate was significantly higher in patients indicating an overall sympathetic dominance and was inversely correlated with diffusion capacity. Serum IL-6 was inversely correlated with pNN50, an index of parasympathetic activity, and positively with LF/HF ratio, a measure of sympathetic: parasympathetic balance. None of the HRV indices was significantly correlated with physiological measures of severity. It was concluded that patients with COPD have increased cardiac autonomic modulation with sympathetic dominance. This is associated with decreased lung diffusion capacity and systemic inflammation.

NK1-receptor-expressing paraventricular nucleus neurones modulate daily variation in heart rate and stress-induced changes in heart rate variability.

The paraventricular nucleus of the hypothalamus (PVN) is an established center of cardiovascular control, receiving projections from other nuclei of the hypothalamus such as the dorsomedial hypothalamus and the suprachiasmatic nucleus. The PVN contains a population of “pre‐autonomic neurones” which project to the intermediolateralis of the spinal cord and increase sympathetic activity, blood pressure, and heart rate. These spinally projecting neurones express a number of membrane receptors including GABA and substance P NK1 receptors. Activation of NK1‐expressing neurones increases heart rate, blood pressure, and sympathetic activity. However, their role in the pattern of overall cardiovascular control remains unknown. In this work, we use specific saporin lesion of NK1‐expressing PVN rat neurones with SSP‐SAP and telemetrically measure resting heart rate and heart rate variability (HRV) parameters in response to mild psychological stress. The HRV parameter “low frequency/high frequency ratio” is often used as an indicator of sympathetic activity and is significantly increased with psychological stress in control rats (0.84 ± 0.14 to 2.02 ± 0.15; P < 0.001; n = 3). We find the stress‐induced increase in this parameter to be blunted in the SSP‐SAP‐lesioned rats (0.83 ± 0.09 to 0.93 ± 0.21; P > 0.05; n = 3). We also find a shift in daily variation of heart rate rhythm and conclude that NK1‐expressing PVN neurones are involved with coupling of the cardiovascular system to daily heart rate variation and the sympathetic response to psychological stress.

Neural and sympathetic activity associated with exploration in decision-making: further evidence for involvement of insula.

We previously reported that sympathetic activity was associated with exploration in decision-making indexed by entropy, which is a concept in information theory and indexes randomness of choices or the degree of deviation from sticking to recent experiences of gains and losses, and that activation of the anterior insula mediated this association. The current study aims to replicate and to expand these findings in a situation where contingency between options and outcomes is manipulated. Sixteen participants performed a stochastic decision-making task in which we manipulated a condition with low uncertainty of gain/loss (contingent-reward condition) and a condition with high uncertainty of gain/loss (random-reward condition). Regional cerebral blood flow was measured by 15O-water positron emission tomography (PET), and cardiovascular parameters and catecholamine in the peripheral blood were measured, during the task. In the contingent-reward condition, norepinephrine as an index of sympathetic activity was positively correlated with entropy indicating exploration in decision-making. Norepinephrine was negatively correlated with neural activity in the right posterior insula, rostral anterior cingulate cortex, and dorsal pons, suggesting neural bases for detecting changes of bodily states. Furthermore, right anterior insular activity was negatively correlated with entropy, suggesting influences on exploration in decision-making. By contrast, in the random-reward condition, entropy correlated with activity in the dorsolateral prefrontal and parietal cortices but not with sympathetic activity. These findings suggest that influences of sympathetic activity on exploration in decision-making and its underlying neural mechanisms might be dependent on the degree of uncertainty of situations.

Two new indexes for the assessment of autonomic balance in elite soccer players.

The application of Poincaré-plot analysis to heart-rate variability (HRV) is a common method for the assessment of autonomic balance. However, results obtained from the indexes provided by this analysis tend to be difficult to interpret. In this study the authors aimed to prove the usefulness of 2 new indexes: the stress score (SS) and the sympathetic:parasympathetic ratio (S:PS ratio). 25 professional Spanish soccer players from same team underwent 330 resting measurements of HRV. All subjects experienced 10 min of HRV monitoring through an R-R-interval recorder. The following parameters were calculated: (1) Poincaré-plot indexes: SD1 (transverse axis), which is proportional to parasympathetic activity; SD2 (longitudinal axis), which is inversely proportional to sympathetic activity; and the SD1:SD2 ratio; (2) time-domain parameters: standard deviation of R-R intervals (SDNN), root-mean-square differences of successive heartbeat intervals (rMSSD), and percentage of successive R-R-interval pairs differing in more than 50 ms in the entire recording divided by the total number of R-R intervals (pNN50); and (3) the proposed 2 new indexes: the SS and the S:PS ratio. The study found a high negative correlation between the SS and SDNN (R2=.94). The S:PS ratio correlated inversely to rMSSD (R2=.95), SDNN (R2=.94), and pNN50 (R2=.74). The S:PS ratio showed a strong correlation with SD1 (R2=.95) and SS (r=.87, R2=.88). The application of the SS as sympathetic-activity index and the S:PS ratio as a representation of autonomic balance (SS:SD1) provides a better understanding of the Poincaré-plot method in HRV.

Plasma and erythrocyte relationship of catecholamines in hemodialysis patients.

The function of the autonomic nervous system is based on reciprocal interaction between the sympathetic and parasympathetic parts, most frequently in the form of antagonistic action on target organs. The main mediators of the sympathetic nervous system in the effectors part are catecholamines (CA), which are involved in various physiological processes. Moreover, CA also has a profound effect on the kidneys, being factors that impact on renal haemodynamics, and have been reported to be altered in pathological disorders, e.g. extracellular volume expression, hypertension and cardiovascular complications. The increased sympathetic nerve activity, at least in part, can explain the raised in plasma CA observed in chronic kidney diseases. Furthermore, plasma CA levels in ureamic patients cannot be considered a reliable index of sympathetic activity, due to existence of many factors which may affect their values. In addition, CA released into the circulation, as one of many substances, may penetrate across the cellular membranes of erytrocytes (RBC). Taking these observations together, the aim of the presented study was to investigate for the first time the plasma and erythrocyte relationship of catecholamines in haemodialysis. The studies were performed among 37 haemodialysed patients who were inhabitants of the Lublin commune. Plasma and intracellular concentration of CA were measured prior to and following haemodialysis by high performance liquid chromatography with electrochemical detection. The results suggest that RBC are able to accumulate CA at the stage of terminal renal failure; in addition, the levels of adrenaline and dopamine in RBC depend on the accumulation of urea in plasma. It was also found that the dynamic changes in concentration of RBC adrenaline are an independent predictor of mortality in haemodialysis patients.

Abstract 204: Non-dipper Pattern Is Associated With Urinary Metanephrines In Patients With Refractory Hypertension

Refractory hypertension (HTN) is an extreme phenotype of treatment-resistant HTN and is defined as blood pressure (BP) ≥140/90 mm Hg on ≥5 antihypertensive drug classes including a diuretic and mineralocorticoid antagonist. Observational data indicate that African Americans, males, body mass index, kidney function, and diabetes are associated with refractory HTN. Available BP data of refractory HTN are based on clinic or in-home evaluations. Less is known about ambulatory blood pressure (ABP) levels, circadian patterns and pathophysiologic mechanisms. Aim: Prospective study of ABP levels, nocturnal BP fall, and urinary (U-) 24-hour metanephrines as index of sympathetic activity. Methods: Over a 2 year period, 44 subjects were prospectively enrolled (15 subjects with refractory HTN matched with 29 controlled resistant hypertensive subjects who served as comparator group). All subjects underwent 24-ABP monitoring (ABPM) and U-24-hour metanephrines testing. Results: Subjects with refractory HTN were on more antihypertensive drugs (6±1 vs 4.1±1.1, p≤ 0.05) and had significantly higher 24-hour systolic BP(SBP) (174±20.2 vs 139.8±16.3 mm Hg, p=0.0017), higher 24-hour diastolic BP (DBP) (94.7±19.8 vs 75.7±11.8 mm Hg, p=0.006), higher daytime SBP (178.1±97.4 vs 141±15.7 mm Hg, p=0.0046), higher daytime DBP (97.4±19.8 vs 77.2±11.4 mm Hg, p=0.007), higher nighttime SBP (165.2±19.2 vs 133.5±19.8 mm Hg, p=0.0002), and higher nighttime DBP (87.7±16.5 vs 70.2±15.1 mm Hg, p=0.007). Analysis of circadian patterns revealed significant increase in non-dipper pattern, defined as nocturnal BP fall of 0-10%, in subjects with refractory HTN (53.3 % (8 of 15) vs 14.3 % (3 of 28), p=0.0267). Biochemical analysis of U-24-hr fractionated metanephrines revealed significantly higher levels in refractory compared to controlled resistant HTN indicative of higher sympathetic activity (U-24-h total metanephrines (592.2 ±246.9 vs 409.3±167.0 μg, p=0.021, and U-24-h total normetanephrines 464.4 ±250.2 vs 309.8±147.6 μg, p=0.039). These findings suggest that increased sympathetic activity may play a role in treatment failure and may promote blunted nocturnal BP fall in refractory hypertension.