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α-肾上腺素受体分为两种亚型与神经递质释放的突触前控制学说密切相关。用在体和离体制备证实,激活位于神经末梢的α-受体可抑制交感神经兴奋时去甲肾上腺素的释放。此发现使有必要区别肾上腺素能神经末梢的抑制性受体和已知调节血管平滑肌对儿茶酚胺产生收缩反应的经典α-受体。采用解剖术语,神经元的α-受体定名为突触前α-受体;而效应器细胞上的受体称为突触后α-受体。对突触前α-受体的特性与功能研究表明,突触前和突触后的α-
There are two subtypes of α-adrenergic receptors that are closely related to the presynaptic hypothesis of neurotransmitter release. It has been demonstrated in vivo and ex vivo that activation of α-receptors located at the nerve terminals suppresses the release of norepinephrine during sympathetic excitation. This finding makes it necessary to distinguish between inhibitory receptors for adrenergic nerve endings and classical alpha-receptors known to modulate the contractile response of vascular smooth muscle to catecholamines. In anatomical terms, a-receptors for neurons are designated pre-synaptic a-receptors; and receptors on effector cells are termed postsynaptic a-receptors. Studies on the properties and functions of pre-synaptic a-receptors show that presynaptic and postsynaptic α-