NEURONAL CONTROL OF AIRWAYS SMOOTH-MUSCLE

Sensory afferent nerves relay impulses from the airways to the central nervous system so that appropriate changes in bronchomotor tone and b reathing patterns may occur. The dominant efferent control of airways smooth muscle is exerted via bronchoconstrictor parasympathetic cholin ergic nerves. In some species this is opposed by bronchodilator sympat hetic noradrenergic nerves. In addition, there exist both excitatory b ronchoconstrictor and inhibitory bronchodilator non-adrenergic, non-ch olinergic pathways. This review examines the role of the different bra nches of the autonomic nervous system in the control of airways smooth muscle tone with particular reference to modulation of these branches and the interactions which may exist between them.