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Sympathetic Nervous Activity (sympathetic + nervous_activity)
Selected AbstractsCorrelation between electroencephalography and heart rate variability during sleepPSYCHIATRY AND CLINICAL NEUROSCIENCES, Issue 1 2003MMLSC , Mina Ako MT Abstract It is known that autonomic nervous activities change in correspondence with sleep stages. However, the characteristics of continuous fluctuations in nocturnal autonomic nerve tone have not been clarified in detail. The study aimed to determine the possible correlation between the electroencephalogram (EEG) and autonomic nervous activities, and to clarify in detail the nocturnal fluctuations in autonomic nerve activities. Overnight EEGs and electrocardiograms of seven healthy males were obtained. These EEGs were analyzed by fast Fourier transformation algorithm to extract delta, sigma and beta power. Heart rate and heart rate variability (HRV) were calculated in consecutive 5-min epochs. The HRV indices of low frequency (LF), high frequency (HF) and LF/HF ratio were calculated from the spectral analysis of R-R intervals. The sleep stages were manually scored according to Rechtschaffen and Kales' criteria. Low frequency and LF/HF were significantly lower during non-rapid eye movement (NREM) than REM, and were lower in stages 3 and 4 than in stages 1 and 2. Furthermore, delta EEG showed inverse correlations with LF (r = , 0.44, P < 0.001) and LF/HF (r = , 0.41, P < 0.001). In contrast, HF differed neither between REM and NREM nor among NREM sleep stages. Detailed analysis revealed that correlation was evident from the first to third NREM, but not in the fourth and fifth NREM. Delta EEG power showed negative correlations with LF and LF/HF, suggesting that sympathetic nervous activities continuously fluctuate in accordance with sleep deepening and lightening. [source] Forearm vascular and neuroendocrine responses to graded water immersion in humansACTA PHYSIOLOGICA, Issue 2 2000Gabrielsen The hypothesis that graded expansion of central blood volume by water immersion to the xiphoid process and neck would elicit a graded decrease in forearm vascular resistance was tested. Central venous pressure increased (P < 0.05) by 4.2 ± 0.4 mmHg (mean ± SEM) during xiphoid immersion and by 10.4 ± 0.5 mmHg during neck immersion. Plasma noradrenaline was gradually suppressed (P < 0.05) by 62 ± 8 and 104 ± 11 pg mL,1 during xiphoid and neck immersion, respectively, indicating a graded suppression of sympathetic nervous activity. Plasma concentrations of arginine vasopressin were suppressed by 1.5 ± 0.5 pg mL,1 (P < 0.05) during xiphoid immersion and by 2.0 ± 0.5 pg mL,1 during neck immersion (P < 0.05 vs. xiphoid immersion). Forearm subcutaneous vascular resistance decreased to the same extent by 26 ± 9 and 28 ± 4% (P < 0.05), respectively, during both immersion procedures, whereas forearm skeletal muscle vascular resistance declined only during neck immersion by 27 ± 6% (P < 0.05). In conclusion, graded central blood volume expansion initiated a graded decrease in sympathetic nervous activity and AVP-release. Changes in forearm subcutaneous vascular resistance, however, were not related to the gradual withdrawal of the sympathetic and neuroendocrine vasoconstrictor activity. Forearm skeletal muscle vasodilatation exhibited a more graded response with a detectable decrease only during immersion to the neck. Therefore, the forearm subcutaneous vasodilator response reaches saturation at a lower degree of central volume expansion than that of forearm skeletal muscle. [source] EXAMINATION OF RESPIRATORY AND CIRCULATORY DYNAMICS DURING EXAMINATION USING A THIN GASTROINTESTINAL ENDOSCOPE IN ADVANCED-AGE SUBJECTSDIGESTIVE ENDOSCOPY, Issue 2 2007Miyako Niki Background:, Endoscopic examination influences cardiovascular hemodynamics. Upper gastrointestinal examinations are currently performed with a thin endoscope. In the present study, respiratory and circulatory dynamics and autonomic nervous activity using a thin endoscope (XP260) or a standard endoscope (XQ240) were investigated. Methods:, The subjects were 25 healthy adults aged less than 60 years (middle-aged group) and 15 healthy adults aged 60 years or older (advanced-age group). Percutaneous oxygen saturation, tonometric blood pressure, heart rate, and autonomic nervous activity were evaluated before the examination. After the endoscopic procedure, a questionnaire survey regarding examination-related stress was conducted. Results:, In the questionnaire survey, the proportion of subjects who answered ,very stress free' in the thin endoscope group was significantly higher than that in the standard endoscope group. The low frequency power of blood pressure variability (LFBP), an indicator of sympathetic nervous activity, was significantly lower during the thin endoscopic procedure than during the standard endoscopic procedure. Moreover, the ratio of low frequency power to high frequency power of heart rate variability (LFRR/HFRR), an indicator of sympathetic nervous activity, was significantly lower during thin endoscopic procedure than during the standard endoscopic procedure. The maximum rates of change in the LFBP and HFRR powers in the advanced-age group using thin and standard endoscopic procedures were significantly lower than in the middle-aged group. Conclusions:, The findings, although not in cross-over study, suggest that a thin endoscope has a less marked influence on circulatory kinetics. Gastrointestinal endoscopic examinations using a thin endoscope might reduce complications related to endoscopic screening examinations in advanced-age subjects. [source] Gastric motility and autonomic activity during obstructive sleep apneaALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 2006M. URATA Summary Background Patients with Obstructive Sleep Apnea Syndrome (OSAS) often experience gastroesophageal reflux disease (GERD). Aim To investigate gastric motility and autonomic nervous activity during sleep apnea. Methods The subjects of this study were 20 individuals with OSAS who experienced 10 or more sleep apnoea events per hour, as measured with a portable sleep polygraph. A percutaneous electrogastrography (EGG) and fast Fourier transformation analysis was carried out on the results. The mean amplitude was compared for bradygastria, normogastria and tachygastria. Spectral analysis of heart rate variability was performed, and low-frequency (LF) power, high-frequency (HF) power and the LF/HF ratio were measured. Oesophagogastroduodenal endoscopy was performed on each subject, and the presence of reflux oesophagitis (RE) was diagnosed according to the Los Angeles (LA) grade classification. Moreover, questionnaire for the diagnosis of reflux disease (QUEST) was carried out. Results Normogastria was significantly decreased, and brady-, tachygastria, or both were increased during sleep apnea (P < 0.01). There was no significant relation between LA grade classification of RE and severity of OSAS. The LF/HF ratio was significantly higher during sleep apnea for patients with RE and OSAS, but the opposite for those with RE without OSAS. Decreased percutaneous arterial oxygen saturation and normogastria were independent risk factors for the severity of RE. Conclusions The present study suggested that, in addition to decreased pressure on the pleural cavity, factors affecting the development of RE might include abnormal gastric motility, low oxygen, and increased sympathetic nervous activity during sleep apnea. [source] Heart rate variability after horse trekking in leading and following horsesANIMAL SCIENCE JOURNAL, Issue 5 2010Akihiro MATSUURA ABSTRACT Horse trekking (HT) is having a stroll on a horse along a walking trail in a forest, field, and/or sandy beach. Generally in HT, horses exercise in tandem line outside the riding facilities. Because the leading horse will be confronted with stressors in the forefront, we hypothesized that the leading horse shows higher stress responses than the following one. In order to verify the hypothesis, we compared short-term stress responses between each position in six horses. Exercise consisted of 15 min of ground riding and 45 min of HT with walking and trotting. Heart rate variability was analyzed for 5 min at 30, 60, and 90 min after the exercising period. There was no significant difference in heart rate during exercise between leading and following positions. The high frequency / low frequency power band of heart rate variability, an index of sympathetic nervous activity, after exercise, tended to be higher in the leading position than following one (P < 0.1). The result in this study can suggest that the leading horse was in a higher stressed state than the following horse after HT. [source] COMPARISON OF ANGIOTENSIN II-INDUCED BLOOD PRESSURE AND STRUCTURAL CHANGES IN FISCHER 344 AND WISTAR KYOTO RATSCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 7 2004Jocelyne Blanc SUMMARY 1.,The purpose of the present study was to evaluate the blood pressure (BP) response, the BP and heart rate (HR) components of the startle reaction and the structure of the carotid artery and the aorta during chronic infusion of angiotensin (Ang) II in Fischer 344 (F344) compared with Wistar Kyoto (WKY) rats, two in-bred normotensive contrasted strains. 2.,Osmotic mini-pumps filled with saline vehicle or AngII (120 ng/kg per min) were implanted subcutaneously in 8-week-old normotensive rats and infused for 4 weeks in F344 rats (saline, n = 10; AngII, n = 10) and WKY rats (saline, n = 10; AngII, n = 9). Basal BP, HR and the responses to an acoustic startle stimulus (duration 0.7 s, 115 dB) were recorded in conscious rats. The structure of the carotid artery and aorta was determined in 4% formaldehyde-fixed arteries. 3.,Compared with WKY rats, vehicle-treated F344 rats had lower bodyweight (BW; 266 ± 7 vs 299 ± 9 g; P < 0.05) and heart weight (0.80 ± 0.02 vs 0.98 ± 0.04 g; P < 0.05) and higher aortic systolic BP (SBP; 131 ± 1 vs 123 ± 5 mmHg; P < 0.001) and diastolic BP (98 ± 3 vs 89 ± 2 mmHg; P < 0.001). In F344 rats, compared with the WKY rats, the wall thickness/BW ratio was increased in the carotid artery (156 ± 9 vs 131 ± 6 nm/g; P < 0.05) and abdominal aorta (264 ± 13 vs 217 ± 12 nm/g; P < 0.05) and decreased in the thoracic aorta (246 ± 13 vs 275 ± 8 nm/g; P < 0.05). There was no difference in elastin and collagen density. Angiotensin II differentially enhanced BP in both strains: (SBP: 163 ± 5 and 132 ± 4 mmHg in F344 and WKY rats, respectively; Pstrain × treatment < 0.05). Circumferential wall stress was increased in the aorta of F344 rats compared with WKY rats (1176 ± 39 vs 956 ± 12 kPa (P < 0.001) and 1107 ± 42 vs 813 ± 12 kPa (P < 0.001) in thoracic and abdominal aortas, respectively). The startle response was amplified in F344 rats, with enhanced increases in SBP and pulse pressure (PP) and bradycardia compared with responses of WKY rats (+44 ± 9 mmHg, +10 ± 2 mmHg and ,40 ± 17 b.p.m., respectively, in F344 rats vs+28 ± 4 mmHg, + 4 ± 2 mmHg and ,19 ± 10 b.p.m. in WKY rats, respectively; Pstrain < 0.05 for BP and PP). The startle response was not affected by AngII. 4.,These results indicate a higher BP producing an increase in wall thickness in F344 rats compared with WKY rats. We propose that an increase in sympathetic nervous activity causes these haemodynamic differences, as suggested by the excessive increase in BP during an acoustic startle stimulus. Angiotensin II increased BP in F344 rats, but did not exaggerate the increase in BP during the startle reaction. [source] Forelimb postischaemic reactive hyperaemia is impaired by hypotensive low body negative pressure in healthy subjectsCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 2 2006Marc Charles Summary Local metabolic conditions adapt blood supply to metabolic requirement by a direct effect on vascular smooth muscles and indirectly by modulating sympathetic vasoconstrictor effectiveness. During exercise, sympathetic nervous activity could in turn interfere on local metabolic control of vascular tone and restrain blood flow to active muscles. In order to investigate that interaction non-invasively, we measured postischaemic reactive hyperaemia (RH) in the forelimb of eight healthy young men (22·7 ± 2·1 years) at rest and during two levels of sympathetic stimulation using low body negative pressure (LBNP ,15 and ,30 mmHg). During every stages, RH was measured after 40, 60, 90 and 180 s of arterial occlusion, respectively. In control conditions, RH rose with duration of ischaemia (18·9, 24·2, 30·4, 33·1 ml min,1 per 100 ml,1 for 40, 60, 90 and 180 s of ischaemia, respectively). During non-hypotensive LBNP (,15 mmHg) sympathetic activation was associated with decreased forelimb blood flow (6·4 ± 0·9 versus 3·9 ± 0·6 ml min,1 per 100 ml,1, P<0·01), but RH were not significantly different from control conditions. During hypotensive tachycardia LBNP (,30 mmHg), RH were significantly lower than under the previous LBNP stage. This fall in RH was greater after the shortest gap of ischaemia and tapered off as arterial occlusion gap increased (,22·3, ,13·1, ,10·5 and ,8·7% for 40, 60, 90 and 180 s of ischaemia, respectively). These results suggested that vascular tone adaptation to local metabolic conditions was modified by sympathetic nervous activation. This was particularly marked when an hypotensive-mediated sympathetic stimulation was opposed to short gaps of ischaemia. [source] | |||||||||||||