Browsing by Subject "Autonomic Nervous System"

Now showing 1 - 4 of 4
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    Autonomic Nerve Activity and Blood Pressure in Ambulatory Dogs
    (Elsevier, 2014-02) Hellyer, Jessica; Akingba, A. George; Rhee, Kyoung-Suk; Tan, Alex Y.; Lane, Kathleen A.; Shen, Changyu; Patel, Jheel; Fishbein, Michael C; Chen, Peng-Sheng; Department of Medicine, IU School of Medicine
    Background The relationship between cardiac autonomic nerve activity and blood pressure (BP) changes in ambulatory dogs is unclear. Objective To test the hypotheses that simultaneous termination of stellate ganglion nerve activity (SGNA) and vagal nerve activity (VNA) predisposes to spontaneous orthostatic hypotension and that specific β2 adrenoceptor blockade prevents the hypotensive episodes. Methods We used a radiotransmitter to record SGNA, VNA and blood pressure (BP) in 8 ambulatory dogs. Video imaging was used to document postural changes. Results Out of these 8 dogs, 5 showed simultaneous sympathovagal discharges in which the minute by minute integrated SGNA correlated with integrated VNA in a linear pattern (“Group 1”). In these dogs abrupt termination of simultaneous SGNA-VNA at the time of postural changes (as documented by video imaging) was followed by abrupt (>20 mmHg over 4 beats) drops in BP. Dogs without simultaneous on/off firing (“Group 2”) did not have drastic drops in pressure. ICI 118,551 (ICI, a specific β2-blocker) infused at 3.1 µg/kg/hr for 7 days significantly increased BP from 126 (95% confidence interval, CI: 118 to 133) mmHg to 133 (95% CI 125 to141) mmHg (p=0.0001). The duration of hypotension (mean systolic BP < 100 mmHg) during baseline accounted for 7.1% of the recording. The percentage was reduced by ICI to 1.3% (p = 0.01). Conclusions Abrupt simultaneous termination of SGNA-VNA was observed at the time of orthostatic hypotension in ambulatory dogs. Selective β2 adrenoceptor blockade increased BP and reduced the duration of hypotension in this model.
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    Role of the Autonomic Nervous System in Atrial Fibrillation: Pathophysiology and Therapy
    (Ovid Technologies Wolters Kluwer -American Heart Association, 2014-04-25) Chen, Peng-Sheng; Chen, Lan S.; Fishbein, Michael C.; Lin, Shien-Fong; Nattel, Stanley; Department of Medicine, IU School of Medicine
    Autonomic nervous system activation can induce significant and heterogeneous changes of atrial electrophysiology and induce atrial tachyarrhythmias, including atrial tachycardia (AT) and atrial fibrillation (AF). The importance of the autonomic nervous system in atrial arrhythmogenesis is also supported by circadian variation in the incidence of symptomatic AF in humans. Methods that reduce autonomic innervation or outflow have been shown to reduce the incidence of spontaneous or induced atrial arrhythmias, suggesting that neuromodulation may be helpful in controlling AF. In this review we focus on the relationship between the autonomic nervous system and the pathophysiology of AF, and the potential benefit and limitations of neuromodulation in the management of this arrhythmia. We conclude that autonomic nerve activity plays an important role in the initiation and maintenance of AF, and modulating autonomic nerve function may contribute to AF control. Potential therapeutic applications include ganglionated plexus ablation, renal sympathetic denervation, cervical vagal nerve stimulation, baroreflex stimulation, cutaneous stimulation, novel drug approaches and biological therapies. While the role of the autonomic nervous system has long been recognized, new science and new technologies promise exciting prospects for the future.
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