Adrenergic antagonists Chapter 11 Adrenergic antagonists 肾上腺素受体拮抗剂剂

Subtypes and effects of adrenergic receptors Presynaptic membrane α2 receptor inhibiting the release of NA β receptor promoting the release of NA α 1受体 Promoting the contracting of the vascular smooth muscle in skin, mucosa, and kidney β受体 β1 receptor excitation of the heart β2受体 Relaxing the smooth muscle of bronchus Relaxing the smooth muscle of coronary artery, and blood vessels in skeletal muscle Negative feedback Positive feedback Pupil dilation  Postsynaptic membrane

α-receptor antagonists Phentolamine [fen'tɔləmi:n] 酚妥拉明 Effects 1 Decreasing blood pressure based on vasodilation effect; 2 Cardiac stimulation based on depressor reflex减压反射: heart contractility ↑, heart rate ↑, cardiac output↑

3 Cholinergic effects: Increasing glandular secretion; promoting the contracting of smooth muscle. 4 Histamine like effects: Increasing gastric acid secretion; lead to skin flush

Uses: 1 Peripheral vascular diseases: Raynaud’s syndrome 雷诺氏综合征, thromboangiitis [,θrɔmbəu,ændʒi'aitis]血栓血管炎; 2 Local vasoconstrictor血管收缩剂 excess; 3 Shock； 4 Pheochromocytoma [fi:əkrəuməsai'təumə]嗜铬细胞瘤; 5 Congestive heart failure.

Adverse effects 1 Postural hypotension (体位性低血压); 2 Tachycardia; 3 Nasal /'neizəl/鼻的 congestion (鼻粘膜充血) ; 4 Gastrointestinal stimulation.

Prazosin /'preizəusin/哌唑嗪 Effects: Block 1 receptor Uses: Hypertension Side effects: Postural hypotension, tachycardia, nasal congestion, drowsiness

-adrenoceptor blocking drugs (-adrenoceptor antagonists) 1 2 receptor blockade effects (1) Heart: 1 blockade→HR↓, heart conductivity↓, contractility↓, CO↓; (2) 2 blockade→ vasoconstriction↑; (3) 2 blockade→ bronchoconstriction [,brɔŋkəukən'strikʃən]支气管狭窄; (4) Renin secretion↓

2 Intrinsic sympathomimetic /,simpəθəumi'metik/拟交感的 activity; 3 Membrane stabilizing activity

Uses: 1 Cardiac arrhythmias; 2 Angina [æn‘dʒaɪnə] pectoris [’pektəris] 心绞痛 3 Hypertension 4 Hyperthyroidism [,haipə'θairɔidizəm]甲亢

Adverse effects Contraindication: 1 Induction or exacerbation [ek,sæsə‘beɪʃən] 恶化of asthma; 2 Inhibition of cardiac function; 3 Withdraw syndrome. Contraindication: Asthma Serious heart failure

Typical drugs Propranolol [prəu'prænə,lɔl]普萘诺尔； Metoprolol [mɪ'tɔprəlɔl] 美托洛尔

大纲要求 Objective and requirements Understand the blocking effects on α and β receptor, and the classification, characteristics, and pharmacological actions of α and β receptor antagonists. Teaching contents Pharmacological effects, mechanism of action, clinical uses of α adrenoreceptor antagonist phentolamine. General description of the pharmacological effects, mechanism of action, clinical use of β adrenoreceptor antagonist propranolol.

Essential vocabulary Adrenergic antagonists Depressor reflex Postural hypotension