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人们早已观察到,随年龄增长,肾上腺素能神经支配的效应器官,如心脏、血管和支气管等,对神经刺激或相应激动剂的反应性逐渐降低。这种现象与频繁神经刺激或反复使用激动剂后,年轻组织器官出现次敏感反应(subsensitive response)非常相似,引起人们极大的注意,并进行了广泛研究。本文就产生这一现象的可能机理作一综合介绍。 效应细胞膜上β-受体数目的变化 许多实验证明,中枢神经系统某些区域的单胺类递质的受体合成随年龄增长而逐渐下降,因而受体密度降低。Wciss等
It has long been observed that with age, effector organs, such as the heart, blood vessels, and bronchial tubes, which are innervated by adrenergic neurons, gradually decrease in response to nerve stimulation or corresponding agonists. This phenomenon is similar to the subsensitive responses of young tissues and organs following frequent nerve stimulation or repeated agonist application, attracting great attention and extensive research. This article gives a comprehensive introduction to the possible mechanisms that lead to this phenomenon. Changes in the number of beta-receptors on the effector membrane Many experiments show that the receptor synthesis of monamine neurotransmitters in some areas of the central nervous system decreases gradually with age and thus decreases the receptor density. Wciss et al