Background: Hyperactivity of the cardiac sympathetic nervous system may underlie the pathogenesis of inappropriate sinus tachycardia (IST). Studies have proven that cervical vagal stimulation could inhibit stellate ganglion neural activity.
Subjects: To investigate whether noninvasive vagal nerve stimulation (NVNS) could inhibit sympathetically induced sinus node acceleration by reducing right stellate ganglion (RSG) neural activity.
Methods: Sixteen anesthetized dogs were randomly divided into NVNS group (with NVNS, n = 8) and control group (with sham NVNS, n = 8). NVNS was delivered to the vagus nerve innervating at the right tragus with a voltage of 80% below the threshold, the minimal voltage to slow the sinus rate or atrioventricular conduction. The maximal sinus rate accelerations induced by high-frequency stimulation (HFS) of RSG and RSG neural activity were measured at baseline and 3 hours after NVNS. At the end, SK2, c-fos, and NGF protein expression in RSG were examined in both groups.
Results: Compared to baseline, the maximal sinus node acceleration induced by RSG stimulation and the RSG neural activity were both significantly attenuated after 3 hours of NVNS (P < 0.05 for both). However, these indices did not change significantly in the control group (P > 0.05). SK2 expression in RSG was significantly higher and c-fos and NGF expressions were significantly lower in the NVNS group than those in the control group (P < 0.05).
Conclusion: Noninvasive vagal nerve stimulation may suppress RSG activity possibly by modulating SK2, c-fos, and NGF expressions in RSG, thus inhibiting sympathetically induced sinus node acceleration.
Keywords: autonomic nervous system; inappropriate sinus tachycardia; noninvasive vagal nerve stimulation; parasympathetic nervous system; right stellate ganglion.
© 2015 Wiley Periodicals, Inc.