11. The vagal and sympathetic activity constantly interact. 12. Each element of the vagal nerve complex links up to a different region of the brainstem. 13. The effect could be blocked using atropine, a known inhibitor to heart vagal nerve stimulation. 14. To be specific, vagal and spinal ganglionic nerves mediate the lowering of the heart rate. 15. Vagal tone cannot be directly measured.16. When hyperstimulated, the left vagal branch predisposes the heart to conduction block at the atrioventricular node. 17. The sympathetic irritant effect is exploited to counteract these vagal parasympathetic effects and thereby reverse the faint. 18. Vagal blockade predictably causes dry mouth, and in men with prostatism, may cause urinary retention.19. Thus, while vagal tone is not explicitly measured, the resultant changes in heart rate are. 20. On the other hand, he said, there is no treatment for abnormalities of the vagal system.
