Airways Smooth Muscle: Structure, Innervation and Neurotransmission (Respiratory Pharmacology and Pharmacotherapy)

Many factors may influence the release of neurotransmitters from airway nerves [1]. This is likely to be important in physiological control of airway functions and may be particularly relevant in airway diseases, such as asthma and chronic obstructive pulmonary disease (COPD). Neural elements in airways interact in a complex manner and the activation of certain neural pathways may profoundly influence the release of transmitters from other neural pathways. Similarly inflamma­ tory mediators released from inflammatory cells in the airways may also modulate neurotransmitter release. There are marked differences be­ tween species in airway innervation and in neuromodulatory effects and, wherever possible, studies in human airways have been emphasised, although information on neuromodulation in human airways is some­ what limited at present. Release of neurotransmitters from nerve terminals occurs via a Ca2+­ dependent secretion evoked by a nerve action potential, but may also be evoked experimentally by a high extracellular K + concentration which directly depolarises the nerve terminal membrane. Modulation refers to the alteration of neurotransmitter release, which may either be increased (facilitation) or reduced (inhibition) by the action of a particular agent, thus changing the magnitude of the neurally-mediated response. Such agents would normally act on receptors on the nerve terminal which are referred to as pre-junctional (or presynaptic) receptors, in contrast to post-junctional (or post-synaptic) receptors located on the target cells which are influenced by that particular transmitter. Front Matter....Pages I-VII Anatomy of Airways Smooth Muscle....Pages 1-27 Role of the Sympathetic Nervous System and Endogenous Catecholamines in the Regulation of Airways Smooth Muscle Tone....Pages 29-41 Parasympathetic Innervation of Airways Smooth Muscle....Pages 43-78 Airways Ganglia....Pages 79-101 Excitatory Nonadrenergic, Noncholinergic Innervation of Airways Smooth Muscle: Role of Peptides....Pages 103-142 Inhibitory Nonadrenergic, Noncholinergic Innervation of Airways Smooth Muscle: Role of Vasoactive Intestinal Peptide and Structurally Related Molecules....Pages 143-156 Inhibitory Nonadrenergic, Noncholinergic Innervation of Airways Smooth Muscle: Role of Nitric Oxide....Pages 157-187 Immunocytochemistry and Molecular Biology in the Identification of Peptide-Containing Nerves....Pages 189-208 Modulation of Neurotransmitter Release from Airways Nerves....Pages 209-259 Autoregulation of Cholinergic Neurotransmission in Airways Nerves....Pages 261-278 Vagal Reflexes....Pages 279-307 Neural Elements in Human Airways....Pages 309-324 Back Matter....Pages 325-328