Autonomic neuroscience : basic & clinical
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We sought to determine whether spinal cord stimulation (SCS) therapy, when applied chronically to canines, imparts long-lasting cardio-protective effects on neurogenic atrial tachyarrhythmia induction and, if so, whether its effects can be attributable to i) changes in intrinsic cardiac (IC) neuronal transmembrane properties vs ii) modification of their interneuronal stochastic interactivity that initiates such pathology. Data derived from canines subjected to long-term SCS [(group 1: studied after 3-4 weeks SCS; n = 5) (group 2: studied after 5 weeks SCS; n = 11)] were compared to data derived from 10 control animals (including 4 sham SCS electrode implantations). During terminal studies conducted under anesthesia, chronotropic and inotropic responses to vagal nerve or stellate ganglion stimulation were similar in all 3 groups. ⋯ Phasic and accommodating right atrial neuronal somata displayed similar passive and active membrane properties in vitro, whether derived from sham or either chronic SCS group. Synaptic efficacy was differentially enhanced in accommodating (not phasic) IC neurons by chronic SCS. Taken together these data indicate that chronic SCS therapy modifies IC neuronal stochastic inter-connectivity in atrial fibrillation suppression by altering synaptic function without directly targeting the transmembrane properties of individual IC neuronal somata.
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Recent studies have shown that vagus nerve activation inhibits cytokine production in a variety of non-neural cells though activation of α7 nicotinic acetylcholine receptor (α7nAChR). Since chronic inflammation plays a pivotal role in liver fibrosis, this study was designed to investigate the role of hepatic vagus nerve in the progression of hepatic fibrosis in rats. Cirrhosis was induced by chronic ligation of the bile duct. ⋯ However neither selective hepatic vagotomy nor methyllycaconitine (an α7nAChR antagonist) could significantly affect development of portal hypertension or hepatic fibrosis in rats. Selective hepatic vagotomy could only attenuate serum aspartate aminotransferase level in bile duct ligated rats but did not have a significant effect on hepatic inflammation as assessed by MCP-1 mRNA expression. Our study provides evidence against a crucial role for the hepatic vagus nerve as an intrinsic protective mechanism in modulation of hepatic fibrosis in a rat model of biliary cirrhosis.
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Controlled Clinical Trial
Transcutaneous vagal nerve stimulation may elicit anti- and pro-nociceptive effects under experimentally-induced pain - a crossover placebo-controlled investigation.
Vagal nerve stimulation is a promising method for the treatment of pain. The aim was to investigate the effect of non-invasive transcutaneous vagal nerve stimulation (TVNS) on the experimental pain threshold (PT) and to compare it with placebo. PT of standardized electrical stimulation was measured in 22 healthy male volunteers during two study sessions. ⋯ Heart rate and blood pressure did not change during the study. Transcutaneous vagal nerve stimulation may produce both anti- and pro-nociceptive effects in healthy volunteers. The individual sensitivity and TVNS parameters might play a role.
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Syncope may be the final common presentation of a number of clinical conditions spanning benign (i.e. neurally-mediated syncope) to life-threatening diseases (i.e. cardiac syncope). Hospitalization rate after a syncopal episode is high. An effective risk stratification is crucial to identify patients at risk of poor prognosis in the short term period to avoid unnecessary hospital admissions. ⋯ A new tool for syncope management is represented by the Syncope Unit in the ED or in an outpatient setting. Syncope Unit may reduce hospitalization and length of hospital stay. However, further studies are needed to clarify whether syncope patients' prognosis can be also improved.
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Sudden cardiac death (SCD) is a common late complication in patients with tetralogy of Fallot (ToF). Reduced baroreflex sensitivity (BRS) is an independent predictor of SCD and BRS reduction was reported in ToF. Relationship between BRS and carotid artery distensibility (DC) in healthy subjects was reported by us earlier. ⋯ We showed that reduced DC may contribute to impaired baroreflex function in ToF patients and could in part explain the elevated risk for SCD postoperatively. Therefore it would be an important future investigation to test carotid artery stiffness and analyze its predictive value for cardiac mortality in ToF. Preventive actions to impede carotid artery stiffening should receive more attention in the clinical management of ToF patients.