Furthermore, muscarinic receptors on blood vessel walls can cause vasorelaxation through a nitric oxide (NO)–modulated pathway but can also cause vasoconstriction by directly activating smooth muscle. Parasympathetic activation can affect atrioventricular nodal conduction mediated predominantly through the left vagus nerve. Cardiovascular effects include heart rate reduction by inhibition of the sympathetic nervous system and by direct hyperpolarization of sinus nodal cells.
Acetylcholine release from parasympathetic nerve terminals will activate ganglionic nicotinic receptors that in turn activate muscarinic receptors at the cellular level. Vagus nerve afferent activation, originating peripherally, can modulate efferent sympathetic and parasympathetic function centrally and at the level of the baroreceptor.Įfferent vagus nerve activation can have tonic and basal effects that inhibit sympathetic activation and release of norepinephrine at the presynaptic level. Chapter 20, by permission of Pearson Education, Inc Prentice Hall, copyright © 2006. Efferent fiber (vagus) comprises A-beta, A-delta, and unmyelinated C fibers. Parasympathetic and sympathetic innervation of the heart: anatomy. Customer Service and Ordering Informationįigure.Stroke: Vascular and Interventional Neurology.Journal of the American Heart Association (JAHA).Circ: Cardiovascular Quality & Outcomes.
Arteriosclerosis, Thrombosis, and Vascular Biology (ATVB).
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