Adrenergic antagonists or adrenergic blocking agents are also called sympatholytic drugs because they lyse, or block, the effects of the sympathetic nervous system (SNS). The therapeutic and adverse effects associated with these drugs are related to their adrenergicreceptor-site specificity; that is, the ability to react with specific adrenergic receptor sites without activating them, thus preventing the typical manifestations of SNS activation. By occupying the adrenergic receptor site, they prevent norepinephrine released from the nerve terminal or from the adrenal medulla from activating the receptor, thus blocking the SNS effects.
The adrenergic blockers have varying degrees of specificity for the adrenergic receptor sites. For example, some can interact with both alpha- and beta-receptors. Some are specific to alpha-receptors, with some being even more specific to just alpha1-receptors. Other adrenergic blockers interact with both beta1- and beta2-receptors, whereas others interact with just either beta1- or beta2-receptors. This specificity allows the clinician to select a drug that will have the desired therapeutic effects without the undesired effects that occur when the entire SNS is blocked. In general, however, the specificity of adrenergic blocking agents depends on the concentration of drug in the body. Most specificity is lost with higher serum drug levels.
Based on their varying degrees of specificity, adrenergic antagonists are classified into five: nonselective adrenergic antagonists, nonselective alpha- and beta- adrenergic antagonists, and selective alpha1– and beta-adrenergic antagonists.
The effects of the adrenergic blocking agents vary with the age of the patient. Various alternative and herbal remedies also can affect these drugs.
肾上腺素能阻滞剂的效应与患者年龄有关。不同的替代和疗法也会影响这些药物效果
★Vocabulary★
adrenergic antagonist – 肾上腺素能拮抗药
adrenergic blocking agent – 肾上腺素能阻滞剂
sympatholytic – a. n. 抗交感神经的（药）
lyse – v. 溶解，渐退
block – v. 阻断，堵塞
SNS -- sympathetic nervous system
specificity – n. 特异性，专一性
occupy – v. 侵占，占据
adrenergic receptor site – 肾上腺素能受体部位
epinephrine – n. 肾上腺素
nerve terminal – 神经末梢
adrenal medulla – 肾上腺髓质
norepinephrine – n. 去甲肾上腺素
nonselective – a. 非选择性的
selective – a. 选择性的
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★Video ★
Adrenergic Antagonists
★Test ★
1. The drugs that mimic the effect of norepinephrine are called:
A. Sympathomimetics, or adrenergic agonists.
B. Sympatholytics, or adrenergic drugs.
C. Sympathomimetics, or adrenergic blockers.
D. Sympatholytics, or adrenergic blockers.
2. The actions of the mixed-acting sympathomimetics are _____ the adrenergic receptor sites and _____ the release of norepinephrine.
A. Stimulating; inhibiting
B. Stimulating; stimulating
C. Inhibiting; inhibiting
D. Inhibiting; stimulating
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答案 Answers
1. A. Sympathomimetics, or adrenergic agonists. Rationale: Drugs that stimulate the sympathetic nervous system are called adrenergic agonists.
2. B. Stimulating; stimulating Rationale: Mixed-acting agents stimulate the release of norepinephrine and directly stimulate alpha and beta receptors.
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