阿摩線上測驗
44 Phenoxybenzamine 之抑制 α 受體主要是經由下列何者而產生？
(A)Allosteric inhibition
(B)Competitive inhibition
(C)Alkylation
(D)Acylation
答案：登入後查看
統計： A(415), B(518), C(1231), D(195), E(0) #415711
統計： A(415), B(518), C(1231), D(195), E(0) #415711
詳解 (共 6 筆)
Pharm+
#2903392
3.下列何種藥物會與其作用之標的（target）產生共價結合？
(A)Phenoxybenzamine
(B)Phenylephrine
(C)Physostigmine
(D)Pilocarpine
34
2
所得皆所愿
#5119396
補充共價鍵結：
| 種類 | α-antagonist | 抗腫瘤 | 抗憂鬱 | Loop | 不可逆AcHEI |
| 藥物 | Phenoxybenzamine | 烷化劑：Mechlorethamine 抗代謝：5-FU | MAOI -B：Selegiline | Ethacrynic acid | 有機磷殺蟲劑：Parathion |
15
1
我愛阿摩，阿摩愛我2
#1070021
Phenoxybenzamine is used as an anti-hypertensive due to its efficacy in reducing the vasoconstriction caused by epinephrine (adrenaline) and norepinephrine. Phenoxybenzamine forms a permanent covalent bond with adrenergic receptors. Based on known information about the structures of these receptors, it likely involves attack by the cysteine at position 3.36 in transmembrane helix 3 to form a stable linkage.[6] Thus, it remains permanently bound to the receptor, preventing adrenaline and noradrenaline from binding. This causes vasodilatation in blood vessels, due to its antagonistic effect at the alpha-1 adrenoceptor found in the walls of blood vessels, resulting in a drop in blood pressure. A side effect of phenoxybenzamine is reflex tachycardia.
As a non-selective alpha receptor antagonist, it will also affect both the postsynaptic alpha 1 and presynaptic alpha 2 receptors in the nervous system, and so reduce sympathetic activity. This results in further vasodilation, pupil constriction, an increase in GI tract motility and secretions, and glycogen synthesis.
It also has partial agonist/antagonist properties at the serotonin 5-HT2A receptor. Due to its 5-HT2A antagonism, it is useful in the treatment of carcinoid tumor, a neoplasm that secretes large amounts of serotonin and causes diarrhea, bronchoconstriction, and flushing.
As a non-selective alpha receptor antagonist, it will also affect both the postsynaptic alpha 1 and presynaptic alpha 2 receptors in the nervous system, and so reduce sympathetic activity. This results in further vasodilation, pupil constriction, an increase in GI tract motility and secretions, and glycogen synthesis.
It also has partial agonist/antagonist properties at the serotonin 5-HT2A receptor. Due to its 5-HT2A antagonism, it is useful in the treatment of carcinoid tumor, a neoplasm that secretes large amounts of serotonin and causes diarrhea, bronchoconstriction, and flushing.
6
8
