Rate Variability Power Spectral Analysis Research Articles

Effect of Head-Up/-Down Tilt on ECG Segments and Myocardial Temporal Dispersion in Healthy Subjects.

The head-up/-down tilt test acutely modifies the autonomic nervous system balance throughout a deactivation of the cardiopulmonary reflexes. The present study examines the influence of head-up/-down tilt on a number of ECG segments. A total of 20 healthy subjects underwent a 5 min ECG and noninvasive hemodynamic bio-impedance recording, during free and controlled breathing, lying at (a) 0°; (b) -45°, tilting up at 45°, and tilting up at 90°. Heart rate variability power spectral analysis was obtained throughout some ECG intervals: P-P (P), P-Q (PQ), PeQ (from the end of P to Q wave), Q-R peak (QR intervals), Q-R-S (QRS), Q-T peak (QTp), Q-T end (QTe), STp, STe, T peak-T end (Te), and, eventually, the TeP segments (from the end of T to the next P waves). Results: In all study conditions, the Low Frequency/High FrequencyPP and LFPP normalized units (nu) were significantly lower than the LF/HFRR and LFRRnu, respectively. Conversely, the HFPP and HFPPnu were significantly higher in all study conditions. STe, QTp, and QTe were significantly related to the PP and RR intervals, whereas the T wave amplitude was inversely related to the standard deviations of all the myocardial repolarization variables and to the left ventricular end-systolic volume (LVEDV). The T wave amplitude diminished during head-up tilt and significantly correlated with the LVEDV.

Effect of Tryptophan, Vitamin B6, and Nicotinamide-Containing Supplement Loading between Meals on Mood and Autonomic Nervous System Activity in Young Adults with Subclinical Depression: A Randomized, Double-Blind, and Placebo-Controlled Study.

Tryptophan (TRP), a precursor of serotonin is believed to have an antidepressant effect. The pathway for brain uptake of TRP is shared by other large neutral amino acids; therefore, the best time to take TRP may be between meals. No previous study has, however, designated the time of TRP dosing to improve mood. Further, the effects of TRP on autonomic nervous system (ANS) activity are unclear. This study investigated the effects of TRP, vitamin B6, and nicotinamide-containing supplements loading between meals on mood and ANS activity in depressive young adults. Thirty depressive young adults were randomly allocated to receive TRP, vitamin B6, and nicotinamide-containing supplements or a placebo supplements twice daily between meals for 7 d. Mood was measured using the Center for Epidemiologic Studies Depression Scale (CES-D) and the Profile of Mood States (POMS). ANS activities were analyzed by heart rate variability power spectral analysis. Blood samples were assayed for plasma total TRP concentration. For analysis, TRP and placebo groups were further classified into two subgroups according to CES-D score (mild to moderate vs. severe depressive symptoms). The CES-D score significantly improved following both treatments in the severe depression subgroups, while the POMS depression score was significantly improved only in the TRP severe depression subgroup. There was no significant change in ANS activity or plasma total TRP in any group. TRP, vitamin B6, and nicotinamide-containing supplements loading between meals can quickly improve depressed mood in quite low dose in young adults with severe subclinical depression.

Myocardial repolarization dispersion and autonomic nerve activity in a canine experimental acute myocardial infarction model.

Evidence from a canine experimental acute myocardial infarction (MI) model shows that until the seventh week after MI, the relationship between stellate ganglion nerve activity (SGNA) and vagal nerve activity (VNA) progressively increases. The purpose of this study was to evaluate how autonomic nervous system activity influences temporal myocardial repolarization dispersion at this period. We analyzed autonomic nerve activity as well as QT and RR variability from recordings previously obtained in nine dogs. From a total of 48 short-term ECG segments, 24 recorded before and 24 recorded 7 weeks after experimentally-induced MI, we obtained three indices of temporal myocardial repolarization dispersion: QTe (from Q-wave to T-wave end), QTp (from Q-wave to T-wave peak), and Te (from T-wave peak to T-wave end) variability index (QTeVI, QTpVI, TeVI). We also performed heart rate variability power spectral analysis on the same segments. After MI, all the QT variables increased QTeVI (median [interquartile range]) (from -1.76[0.82] to -1.32[0.68]), QTeVI (from -1.90[1.01] to -1.45[0.78]), and TeVI (from -0.72[0.67] to -0.22[1.00]), whereas all RR spectral indices decreased (P <.001 for all). Distinct circadian rhythms in QTeVI (P <.05,) QTpVI (P <.001) and TeVI (P <.05) appeared after MI with circadian variations resembling that of SGNA/VNA. The morning QTpVI and TeVI acrophases approached the SGNA/VNA acrophase. Conversely, the evening QTeVI acrophase coincided with another SGNA/VNA peak. After MI, regression analysis detected a positive relationship between SGNA/VNA and TeVI (R(2): 0.077; β: 0.278; p< 0.001). Temporal myocardial repolarization dispersion shows a circadian variation after MI reaching its peak at a time when sympathetic is highest and vagal activity lowest.

Uncoupling protein 1 gene −3826 A/G polymorphism is associated with weight loss on a short-term, controlled-energy diet in young women

Uncoupling protein 1 (UCP1) plays an important role in thermogenesis in brown adipose tissue. Previously, we reported an association between -3826 A/G single-nucleotide polymorphism (SNP) in the promoter of UCP1 gene and lower thermogenesis in young women, suggesting this SNP has an adverse effect on the regulation of energy balance. Based on the hypothesis that this SNP (G allele) may have resistance against diet-induced weight loss, we examined its effects on anthropometric and metabolic responses to short-term, controlled-energy diet in young women. Seventeen lean women (20.9 ± 0.2 years; body mass index, 22.1 ± 0.5 kg/m(2)) were fed a controlled-energy diet (5.0 MJ/d, 62% carbohydrate, 19% protein, and 19% fat) administered by dietitians for 2 weeks. Clinical measurements were determined at baseline and after the dietary intervention. The subjects' physical activity was obtained using pedometers and self-reporting. The thermoregulatory sympathetic nervous system was evaluated using heart rate variability power spectral analysis. Upon the completion of the intervention, subjects were genotyped using an allele-specific DNA primer assay and results compared with their clinical measurements focusing on with or without the G allele. After dietary intervention, G allele subjects (A/G + G/G, n = 10) showed significantly smaller changes in body weight, body mass index, and waist circumference compared with A/A genotype subjects (n = 7). Similar changes were observed in parameters regarding glucose or lipid metabolism in both groups. These results suggest that the UCP1 gene -3826 G allele may result in smaller weight loss after a short-term, controlled-energy diet in young, lean women.

UCP1 genetic polymorphism (–3826 A/G) diminishes resting energy expenditure and thermoregulatory sympathetic nervous system activity in young females

Recent findings regarding the existence of functional brown adipose tissue (BAT) in adult humans suggest a physiological role of BAT and uncoupling protein 1 (UCP1)-linked thermogenesis in energy balance. To investigate whether UCP1 polymorphism was associated with resting energy expenditure (REE) and thermoregulatory sympathetic nervous system (SNS) activity in humans. A total of 82 healthy females (20-22 years) were genotyped for the -3826 A/G polymorphism of the UCP1 gene using a fluorescent allele-specific DNA primer assay system. REE was measured by indirect calorimetry. The thermoregulatory SNS activity was assessed by heart rate variability power spectral analysis according to our previously reported method. Each subject was studied in the morning, after an overnight fast. Nutritional values were calculated on the basis of 2-day food records. The frequencies of A/A, A/G and G/G genotypes were 0.27, 0.45 and 0.28, respectively. No significant difference was found in anthropometric indexes among the three groups. However, in the G/G group, the percentage of energy consumed as fat was lower (A/A: 30.7 ± 1.1%, A/G: 31.3 ± 1.0%, G/G: 26.0 ± 1.2%, P<0.01), and energy intake tended to be lower (A/A: 7209 ± 310 kJ d(-1), A/G: 7075 ± 280 kJ d(-1), G/G: 6414 ± 264 kJ d(-1), P=0.16). With regard to metabolic parameters, group differences were observed in REE (A/A: 5599 ± 170 kJ d(-1), A/G: 5054 ± 115 kJ d(-1), G/G: 4919 ± 182 kJ d(-1), P<0.01) and in thermoregulatory SNS activity (A/A: 313 ± 47 ms(2), A/G: 333 ± 42 ms(2), G/G: 185 ± 23 ms(2), P<0.05). Diminished REE in G-allele carriers as well as reduced thermoregulatory SNS activity for the G/G genotype, suggest that attenuated UCP1-linked thermogenesis has an adverse effect on the regulation of energy balance.

Effects of Dietary Supplementation with a Compound Composed of Caffeine, Capsaicin, Sesamine, L-Carnitine, Banaba and Lotus on Human Autonomic Nervous System Activity and Lipid Oxidation

This study was conducted to determine if supplementation with a compound composed of caffeine (50 ㎎), capsaicin (75 ㎎), sesamine (30 ㎎), L-carnitine (300 ㎎), banaba (50 ㎎) and lotus (10 ㎎) enhanced human autonomic nervous activities (ANS) associated with thermogenic sympathetic activity and fat utilization. Ten healthy college males (21.2±1.0 yr) volunteered for this experiment. Autonomic nervous activities associated with energy metabolism were examined at 30 min intervals for a total of 120-min while at rest and every 5-min during exercise at 50% of the ventilation threshold before and after intake of the compound or placebo with 100 ml of water for 10 days. In addition, heart rate variability power spectral analysis was used to assess human autonomic nervous activities. The results indicated that there were no significant differences in heart rate during rest and exercise among trials. Furthermore, the autonomic nervous activity tended to increase after 10-days of consumption of the test compounds during the experimental period, but the differences did not reach statistical significance. However, before and after the compound test trial there was a significantly higher respiratory gas exchange ratio (rest 0: 0.83±0.01 vs. rest 3: 0.89±0.02, p＜0.05), carbohydrate oxidation (CHO) rate (rest 0: 44.57±5.83 vs. rest 2: 63.86±5.91%, p＜0.05) and a lower fat oxidation rate (rest 0: 55.43±5.83 vs. rest 2: 36.14±5.91%, p＜0.05. In conclusion, the results of the present study suggested that the compound composed of caffeine, capsaicin, sesamine, L-carnitine, banaba and lotus components that was evaluated in this study did not induce a significant increase in human autonomic nervous activities or lipolysis, even though the individual components have been reported to induce increased fat oxidation.

Thermoregulatory sympathetic nervous system activity and diet‐induced waist‐circumference reduction in obese Japanese women

The present study is designed to investigate how and to what extent sympathovagal behavior in a balanced low-calorie diet relates to favorable changes of body mass, waist circumference, and/or metabolic risk factors. The study involved 28 mildly obese women without clinical complications, who underwent an 8-week calorie restriction program using a 1,200-kcal daily diet with an adequate nutrient content; including two regular meals, and one formula meal replacement. All subjects were examined before and after the dietary intervention. We measured anthropometric parameters, blood pressure, and biochemical blood profiles for lipid metabolism. Autonomic nervous system activity was evaluated by heart rate variability power spectral analysis. The dietary intervention induced moderate, but significant reduction of waist circumference (-5.3% +/- 0.8%), body fat percentage (-5.8% +/- 0.8%), and body mass (-6.6% +/- 0.5%). Linear regression analysis showed that Deltavery low frequency (VLF) power reflecting energy metabolic- and thermoregulatory sympathetic function significantly correlated to Deltawaist circumference (r = -0.53, P < 0.01), Deltabody fat percentage (r = -0.39, P < 0.05), Deltabody mass (r = -0.43, P < 0.05), DeltaHDL-cholesterol/total cholesterol ratio (HDL-C/TC) (r = 0.62, P < 0.001), and Deltanonesterified fatty acids (NEFA) (r = 0.56, P < 0.01). A stepwise multiple regression analysis additionally revealed that Deltawaist circumference (P = 0.024), DeltaHDL-C/TC (P = 0.013), and DeltaNEFA (P = 0.016) were significant and independent factors, which contributing to the variance in DeltaVLF power (r(2) = 0.61). Although causes and consequences of obesity continue to elude researchers, the present study indicates that thermoregulatory sympathetic activity relates to moderate waist-circumference reduction together with favorable changes of blood lipid profiles after short-term dietary modification in mildly obese women.

The Combined Effects of Capsaicin, Green Tea Extract and Chicken Essence Tablets on Human Autonomic Nervous System Activity

The purpose of this study was to investigate whether combined capsaicin, green tea, and chicken essence tablets (CCGC) enhance human autonomic nervous activities (ANS) associated with thermogenic sympathetic activity without any adverse effect on the cardiac depolarization-repolarization period. Six healthy males (25.2 +/-1.7 y) volunteered for this experiment. Autonomic nervous activities were examined 5-min at rest per 30-min for total 1.5 h after consuming chicken or CCGC or placebo tablets at random on separate days. Using heart rate variability power spectral analysis, we assessed human autonomic nervous activities. In comparison to chicken essence or placebo tablets, it was observed that the consumption of CCGC significantly increased human autonomic nervous activities [Total power representing over-all ANS activity; CCGC trial 160.2 (50.0) vs. placebo 92.8 (53.3)%, p < 0.05; VLF, very low-frequency power associated with thermogenic sympathetic activity: CCGC trial 235.5 (101.7) vs. chicken 130.5 (52.9)%, p < 0.05; LF, low frequency power representing combined sympatho-vagal activity: CCGC trial 199.8 (59.8) vs. placebo 120.6 (49.2)%, p < 0.05] at 60-min and 90-min. There were no significant differences in heart rate corrected cardiac recovery time (RTc) or QT interval (QTc). In conclusion, the consumption of CCGC enhances thermogenic sympathetic activity compared to that of chicken essence or placebo tablets. Therefore, these results suggest that combined capsaicin, green tea, and chicken essence tablets may be a beneficial food ingredient improving human autonomic nervous activities, particularly thermogenic sympathetic activity as a modulator of energy metabolism without any adverse effects on cardiac electrical stability.

Sympatho-vagal activities during the menstrual cycle of eumenorrheic women with premenstrual symptomatology

A majority of menstruating women experience a cyclic recurrence of a constellation of various symptoms in the premenstrual phase. The etiopathogenesis of the phenomenon, however, remains unknown. The present study was designed to evaluate whether the activity of the autonomic nervous system (ANS), which modulates a human's internal environment, is altered during the menstrual cycle of women with premenstrual symptomatology. Thirty healthy young women participated in this study. All subjects were investigated during the follicular and late luteal phases. The ANS activity was assessed by means of heart rate variability power spectral analysis during supine rest. The ANS activity significantly changed in the symptomatic late luteal phase from the non-symptomatic follicular phase only in women who experienced substantial increase (> 20%) in diverse symptoms premenstrually. In addition, the women of this group possessed higher sympathetic nerve activity and lower parasympathetic nerve activity in the late luteal phase compared with the women who experienced less premenstrual symptomatology. The ANS activity in the follicular phase did not differ among the subjects regardless of their premenstrual symptoms. The present study suggests that the altered functioning of ANS in the late luteal phase could be associated with diverse psychosomatic or behavioral symptoms appearing premenstrually.

Autonomic nervous system activity in the late luteal phase of eumenorrheic women with premenstrual symptomatology

The majority of women of reproductive age experience a regular recurrence of various symptoms in the premenstrual phase. The etiopathogenesis of premenstrual symptomatology, however, remains inconclusive. The present study was proposed to evaluate whether the activity of the autonomic nervous system (ANS), which largely contributes to the relative stability of a human's internal environment, is altered during the menstrual cycle of women with premenstrual symptomatology. Thirty eumenorrheic young women participated in this study. All subjects were investigated during the follicular and late luteal phases. The ANS activity was assessed by means of heart rate variability power spectral analysis during supine rest. No intramenstrual cycle differences in the ANS activity were found in women experiencing no or small increases in premenstrual symptoms. In contrast, the sympathetic nervous system (SNS) activity significantly increased and the parasympathetic nervous system (PNS) activity apparently decreased in the late luteal phase in subjects whose premenstrual symptomatology was not unbearable, but substantially increased (>20%) compared to the symptom-free follicular phase. The women with greater degrees of premenstrual distress possessed higher SNS activity and lower PNS activity in the late luteal phase than the women with less symptomatology. The ANS activity in the follicular phase did not differ among the subjects regardless of their premenstrual symptoms. Although causes and consequences continue to elude, the present study provides additional intriguing evidence that the altered functioning of ANS in the late luteal phase could be associated with diverse psychosomatic or behavioral symptoms appearing premenstrually.

Factors influencing heart rate variability power spectral analysis during controlled breathing in patients with chronic heart failure or hypertension and in healthy normotensive subjects.

A decreased LFP (low-frequency power) spectral component of HRV [HR (heart rate) variability] is a risk factor for sudden death in patients with CHF (chronic heart failure). In the present study, we evaluated factors (age, arterial pressures and HR) influencing LFP and HFP (high-frequency power) components in short-term recordings during controlled breathing in patients with CHF or hypertension, and healthy normotensive subjects. In patients with CHF, we also compared LFP values with known markers of sudden death [NYHA (New York Heart Association) class, HR and ejection fraction]. All HRV measures were significantly lower in patients with CHF than in hypertensive and normotensive subjects (P<0.001), and in hypertensive than in normotensive subjects (P<0.05). Stepwise multiple regression analysis showed that, in patients with CHF, LFP was inversely associated with NYHA class (beta=-0.5, P<0.0001) and HR (beta=-0.2, P=0.001) and was positively associated with ejection fraction (beta=0.28, P<0.0001). In patients with CHF, LFP remained unchanged with age. In normotensive and hypertensive subjects, HFP decreased with age, but in patients with CHF it did not. In the >/=60<70 and >/=70 years of age subgroups, we found no difference between HFP in the three groups studied. Hence, in normotensives and hypertensives, LFP tended to diminish with age (beta=-0.4, P<0.0001 in normotensives; beta=-0.4, P<0.001 in hypertensives) and was inversely associated with HR (beta=-0.2, P=0.002 in normotensives; beta=-0.3, P=0.002 in hypertensives). Conversely, in patients with CHF, LFP is predominantly influenced by NYHA class, HR and ejection fraction, but not by age. LFP might therefore increase the sensitivity of factors already used in stratifying the risk of sudden death in patients with CHF.

Autonomic nervous system activity and the state and development of obesity in Japanese school children.

The autonomic nervous system (ANS) plays an important role in regulating energy expenditure and body fat content; however, the extent to which the ANS contributes to pediatric obesity remains inconclusive. The aim of this study was to evaluate whether sympathetic and/or the parasympathetic nerve activities were altered in an obese pediatric population. We further examined a physiological association between the duration of obesity and the sympatho-vagal activities to scrutinize the nature of ANS alteration as a possible etiologic factor of childhood obesity. Forty-two obese and 42 non-obese healthy sedentary school children were carefully selected from 1080 participants initially recruited to this study. The two groups were matched in age, gender, and height. The clinical records of physical characteristics and development of the obese children were retrospectively reviewed to investigate the onset and progression of obesity. The ANS activities were assessed during a resting condition by means of heart rate variability power spectral analysis, which enables us to identify separate frequency components, i.e., total power (TP), low-frequency (LF) power, and high-frequency (HF) power. The spectral powers were then logarithmically transformed for statistical testing. The obese children demonstrated a significantly lower TP (6.77 +/- 0.12 vs. 7.11 +/- 0.04 ln ms(2), p < 0.05), LF power (6.16 +/- 0.12 vs. 6.42 +/- 0.05 ln ms(2), p < 0.05), and HF power (5.84 +/- 0.15 vs. 6.34 +/- 0.07 ln ms(2), p < 0.01) compared with the non-obese children. A partial correlation analysis revealed that the LF and HF powers among 42 obese children were negatively associated with the duration of obesity independent of age (LF: partial r = -0.55, p < 0.001; HF: partial r = -0.40, p < 0.01). The obese children were further subdivided into two groups based on the length of their obesity. All three spectral powers were significantly reduced in the obese group with obesity of >3 years (n = 18) compared to the group with obesity of <3 years. Our data indicate that obese children possess reduced sympathetic as well as parasympathetic nerve activities. Such autonomic depression, which is associated with the duration of obesity, could be a physiological factor promoting the state and development of obesity. These findings further imply that preventing and treating obesity beginning in the childhood years could be an urgent and crucial pediatric public health issue.

Effects of clothing pressure caused by different types of brassieres on autonomic nervous system activity evaluated by heart rate variability power spectral analysis.

The present study was designed to investigate the effects of clothing skin pressures exerted by two different types of brassieres (a conventional higher skin-pressured brassiere and a newly devised low skin-pressured brassiere) on the autonomic nervous system (ANS) activity. Six healthy young women (22.8 +/- 1.4 yrs.) with regular menstrual cycles participated in this study. The ANS activities were assessed by means of heart rate variability power spectral analysis. The skin pressures exerted by the brassieres were measured with an air-pack type contact surface pressure sensor at five different points. The total amount of clothing pressure, and the pressures at the center and the side regions of the brassieres were significantly greater in the high than in the low skin-pressured brassiere (Total 9816.1 +/- 269.0 vs. 6436.8 +/- 252.4 Pa, P < 0.01; Center 2212.1 +/- 336.3 vs. 353.8 +/- 85.8 Pa, P < 0.01; Side 2556.8 +/- 316.1 vs. 1747.2 +/- 199.2 Pa, P < 0.05). Concerning the ANS activity, the Total power, and the very low frequency (VLF) and the high frequency (HF) components were significantly decreased in the high skin-pressured brassiere than those in the low skin-pressured brassiere (Total 531.6 +/- 57.3 vs. 770.5 +/- 54.2 ms2, P < 0.01; VLF 60.7 +/- 14.6 vs. 179.2 +/- 38.1 ms2, P < 0.05; HF 209.5 +/- 33.2 vs. 283.2 +/- 61.5 ms2, P < 0.01). Our data indicate that the higher clothing pressures exerted by a conventional brassiere have a significant negative impact on the ANS activity, which is predominantly attributable to the significant decrease in the parasympathetic as well as the thermoregulatory sympathetic nerve activities. Since the ANS activity plays an important role in modulating the internal environment in the human body, excess clothing pressures caused by constricting types of foundation garments on the body would consequently undermine women's health.

ROLE OF PLASMA LEPTIN AND ??3-ADRENERGIC RECEPTOR IN OBESE AND NON-OBESE YOUNG WOMEN

1898 We examined the interrelationship among plasma leptin concentration, autonomic nervous system (ANS) activity and β3-adrenergic receptor function in 30 age- and height-matched obese (OB) and non-obese (CON) young women. The ANS activity was assessed by heart rate variability power spectral analysis during resting condition. Plasma leptin concentration was 4.1-hold higher in the OB than CON group. A positive correlation was found between leptin concentration and % body fat (r = 0.86, P < 0.01). There was no significant difference in the resting sympatho-vagal activities between the CON and OB groups. Consequently, the sympathetic sensitivity to leptin (the sympathetic nervous system index to leptin ratio) was found to be nearly 10-hold lower in the OB as compared to CON. Although heterozygous Trp64Arg allele of the β3-adrenergic receptor gene was found in 6 out of 15 OB subjects, none of the variables including body composition, ANS activity, plasma leptin concentration, serum lipids, glucose and insulin levels differed between the OB subjects with and without the mutation. This finding indicate that the β3-adrenergic receptor gene mutation may not be a major determinant of the susceptibility of obesity in young population. Our data suggest that peripheral leptin resistance, which may be associated with the reduced sympathetic responsiveness to endogenous leptin, could be an important etiological factor leading to obesity in young women.