Brandt H D
S Afr Med J. 1986 Dec 6;70(12):749-52.
A neuronal cholinergic system is widely distributed in larger airways, particularly around bifurcations. These neurons form efferent pathways from the brainstem ending in the motor end-plate on smooth muscle, and ciliated and mucus-producing cells. Impulses originating in various sensory endings in the airways, from the central nervous system and from many sensory receptors throughout the body, influence the activity of the cholinergic system thereby controlling the patency of the airways and modulating the rate and depth of breathing. A non-neuronal cholinergic system present on mast cells facilitates their degranulation, resulting in the release of chemical mediators. These induce bronchospasm directly but also indirectly by activating the neuronal cholinergic system. Effective bonchodilator drugs are all antagonists of the cholinergic system. The most effective bronchodilators, however, are physiological antagonists of cholinergic and all other known bronchospasm-inducing agents. Such antagonists include beta-adrenergic stimulants and methyl xanthines. Competitive antagonists such as ipratropium which act on muscarinic receptors in the cholinergic motor end-plate are generally less effective. Drugs such as sodium cromoglycate act only prophylactically by reducing the degranulation of mast cells and/or minimizing irritation of airway sensory receptors.
神经元胆碱能系统广泛分布于较大气道，尤其是在分支周围。这些神经元形成从脑干发出的传出通路，终止于平滑肌、纤毛细胞和黏液分泌细胞的运动终板。源于气道各种感觉末梢、中枢神经系统以及全身许多感觉受体的冲动，会影响胆碱能系统的活动，从而控制气道通畅并调节呼吸频率和深度。肥大细胞上存在的非神经元胆碱能系统促进其脱颗粒，导致化学介质释放。这些介质直接诱导支气管痉挛，也通过激活神经元胆碱能系统间接诱导。有效的支气管扩张药物均为胆碱能系统的拮抗剂。然而，最有效的支气管扩张剂是胆碱能和所有其他已知支气管痉挛诱导剂的生理性拮抗剂。此类拮抗剂包括β-肾上腺素能兴奋剂和甲基黄嘌呤。作用于胆碱能运动终板毒蕈碱受体的竞争性拮抗剂如异丙托溴铵通常效果较差。色甘酸钠等药物仅通过减少肥大细胞脱颗粒和/或最小化气道感觉受体刺激起预防作用。
