Autonomic neuroscience : basic & clinical
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The aim of this study was to determine whether pre-treatment of human skin with the alpha(1)-adrenoceptor antagonist terazosin would block vasoconstrictor responses and axon-reflex vasodilatation to the alpha(1)-adrenoceptor agonist methoxamine. Drugs were administered by iontophoresis into the skin of the forearm of 15 healthy participants, and skin blood flow was monitored with a laser Doppler flow probe at the site of methoxamine iontophoresis (to monitor direct vasoconstrictor responses) or 5-10 mm from the site of methoxamine iontophoresis (to monitor axon-reflex vasodilatation). ⋯ Pre-treatment with terazosin blocked vasoconstrictor responses to increasing doses of methoxamine, and also blocked vasodilatation several mm from the site of terazosin and methoxamine administration. These findings support the view that alpha(1)-adrenoceptors play a role in generating axon-reflex vasodilatation, and thus might contribute to local vascular disturbances in acute and chronic inflammation.
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We examined the Hurst exponent of heart rate time series and its relation with the subjective measures of valence and arousal in two groups of subjects. The electrocardiogram (ECG) and the subjective valence and arousal were measured during the administration of emotional film stimuli (happiness, sadness, anger and fear). The results showed that there is a difference in the Hurst exponent for the happiness and sadness conditions but not between the negative emotion conditions (sadness, anger and fear). This seems to indicate that the Hurst exponent is an indicator of subjective valence.
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Obesity is associated with reduced heart rate variability (HRV), reflecting detrimental changes in cardiac regulation by the autonomic nervous system (ANS). Weight loss reverses this change and ANS dysfunction is thought to have a role in obesity-related cardiac pathology. Few studies have examined the influence of weight-reduction (bariatric) surgery on cardiac autonomic control. This study therefore sought to assess longitudinal changes in indices of cardiac autonomic control following two types of bariatric procedure, laparascopic gastric banding (LGB) and biliopancreatic diversion (BPD). ⋯ This pilot study suggests that the mechanism responsible for improving cardiac regulation following bariatric surgery might be the weight loss itself. Furthermore, post-surgery improvement in QTVI implies that weight loss reduces the risk of ventricular arrhythmic events.