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Section III Circulation system
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Overview of Cardiovascular Diseases
Common Cardiac Diseases Abnormal contractility:Heart failures Abnormal rhythms:Arrhythmias Abnormal blood supply:Ischemic heart diseases Myocardial disorders Common vascular diseases Abnormal systematic resistance:Hypertension Dysfunction of coronary vessels:Coronary vascular diseases Dysfunction of cerebral vessels:Cerebral ischemia, hemorrhage Dysfunction of pulmonary vessels:Pulmonary hypertension Dysfunction of peripheral vessels: Peripheral vascular disorder Arteriosclerosis
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Overview of Cardiovascular Drugs
Classification based on target organs/tissues Heart:Heart failures, arrhythmias, cardiac ischemia, over-load of the heart Vessels:Vasodilatation, vasoconstriction, arteriosclerosis Classification based on the mechanisms Ion channels:Ca2+, Na+, K+ channels Receptors:Adrenoreceptors, AT1 receptors, etc. Enzymes:ACEI, Na+-K+-ATPase, HMG-CoA reductase Others:Diuretics
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Chapter 6 Cardiovascular Drugs
Part 1 Drugs affecting ion channels in CVS
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Modes of solute transmembrane transport
ion channel Modes of solute transmembrane transport
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A. General properties of ion channels in CVS
Permeation Selectivity Gating voltage-gated chemically gated: ligand-gated phospharylation-gated mechanosensitive nongated background / leak channels
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Ion transmembrane transport
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Gating mechanisms of ion channels
Chemically gated Ligand-gated Chemically gated Phospharylation-gated: G protein / second massagers Gating mechanisms of ion channels Voltage-gated Mechanosensitive
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A. General properties of ion channels in CVS
Voltage-gated ion channels Na+ channels Ca2+ channels K+ channels
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General structure of ion channels Structure of -subunit
filter voltage sensor General structure of ion channels Structure of -subunit
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Na+ Channels K+ Channels Ca2+ Channels
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A. General properties of ion channels in CVS
Functional regulation of voltage-gated ion channels Activation (open) Inactivation (close)
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Gating modes of ion channels
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Ligand-gated ion channels
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G protein/cyclic nucleotide-gated ion channels
cyclic AMP subunit of G protein
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B. Drugs affecting ion channels in CVS Calcium channel blockers
1. Intracellular free Ca2+ (1) Ca2+ inward flow Voltage-gated: L, T, N, P, Q, R types Chemically gated: NMDA receptor (2) Release of stored Ca2+ IP3 receptor
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Calcium channels
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Box Voltage-gated calcium channels
L-type calcium channels Activated at -10 mV, inactivated at -60~-90 mV; Long lasting opening; Distributed in myocardial and vascular tissues T-type calcium channels Activated at -70 mV, inactivated at -100~-60 mV; Transient opening; Distributed mainly in heart conduction system (S-A node), arterial walls, etc.
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B. Calcium channel blockers
2. Structures and functions of voltage-gated calcium channels 5 subunits: 1, 2, , , 1 subunit is a more important structure 4 domains, 6TM in each domain S4: voltage sensor,,S6: site of drug binding
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Binding sites of antagonists on L-type calcium channels
dihydropyridines verapamil Binding sites of antagonists on L-type calcium channels
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B. Calcium channel blockers
3. Classification of calcium channel blockers Calcium channel blockers: The drugs which selectively act on voltage-gated calcium channels and block influx of Ca2+ Selective calcium channel blockers Dihydropyridines (二氢吡啶类): nifedipine 硝苯地平 nimoldipine 尼莫地平 amlodipine 氨氯地平 Phenylalkylamines (苯烷胺类): verapamil 维拉帕米 Benzothiazepines (苯硫卓类): diltiazem 地尔硫卓 Non-selective calcium channel blockers 艹 艹
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Nifedipine 硝苯地平 Diltiazem 地尔硫卓 Verapamil 维拉帕米
艹 Nifedipine 硝苯地平 Diltiazem 地尔硫卓 Verapamil 维拉帕米
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B. Calcium channel blockers
4. Pharmacological effects (1) Cardiac effects A. Negative inotropic effect: excitation-contraction discoupling B. Negative chronotropic and slowing conduction action: phase 4 of spontaneous depolarization and phase 0 of depolarization of slow response autonomic cells C. Protective effect on cardiac ischemia
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B. Calcium channel blockers
(2) Effects on smooth muscles A. Vascular smooth muscle: relaxing the arterial smooth muscles, especially coronary artery B. Others: smooth muscle of bronchus, gastrointestinal tract, urine tract, uterus
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Mechanism of calcium channel blocker on myocardial and vascular smooth muscle
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B. Calcium channel blockers
(3) Anti-atherosclerosis Alleviating Ca2+ overload Inhibiting proliferation of smooth muscle cells and protein production of arterial matrix Inhibiting lipid peroxidation Decreasing cholesterol level (4) Hemodynamic effects Improving membrane stability of erythrocytes Inhibiting platelet aggregation
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B. Calcium channel blockers
(5) Others Kidney: increasing the blood flow of kidney Endocrine: inhibiting the release of ACTH, TSH, insulin, etc.
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B. Calcium channel blockers
5. Action modes (1) actions on different functional states Activated: verapamil Inactivated: diltiazem Resting: nifedipine (2) Open frequency-dependency Frequency-dependent: verapamil, diltiazem Frequency-independent: nifedipine
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B. Calcium channel blockers
6. Clinical uses (1) Angina pectoris Variant angina: nifedipine Stable angina: verapamil, diltiazem Unstable angina: verapamil, diltiazem, nifedipine + receptor blockers
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B. Calcium channel blockers
(2) Arrhythmias supraventricular tachycardia arrhythmias induced by triggered activity following after-depolarization - verapamil, diltiazem
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B. Calcium channel blockers
(3) Hypertension nifedipine; verapamil, diltiazem Complicated with coronary heart disease, myocardial ischemia, peripheral vascular diseases, bronchial asthma, chronic obstructive pulmonary diseases, etc.
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B. Calcium channel blockers
(4) Cerebrovascular diseases transient ischemic attack, cerebral thrombosis, subarachnoid hemorrhage (5) Others peripheral vascular spasmodic disease, arteriosclerosis etc.
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B. Calcium channel blockers
7. Adverse effects peripheral edema: nifedipine > verapamil > diltiazem symptoms of sympathetic excitation (heart rate increase): nifedipine reduced heart rate: verapamil, diltiazem hypotension: nifedipine Contraindications: hypotension (nifedipine); severe heart failure, sinus bradycardia, atrioventricular block (verapamil, diltiazem)
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B. Calcium channel blockers
8. Special agents Nifedipine 硝苯地平
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B. Calcium channel blockers
(1) Pharmacological effects Vessels: vasodilatation, hypotension, increase of cardiac output Heart: reflex increase of heart rate, weak direct inhibiting effects (2) Clinical uses Angina pectoris; hypertension; peripheral vascular diseases; etc. Slow releasing forms: adverse effects ; action duration (3) Adverse effects Hypotension; tachycardia; edema; headache, flushing, etc.
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B. Calcium channel blockers Selectively acting on cerebral vasculature
Nimodipine 尼莫地平 Selectively acting on cerebral vasculature
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B. Calcium channel blockers
Verapamil 维拉帕米 Potent efficacy on the heart, and weak on the vessels
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Diltiazem 地尔硫卓 B. Calcium channel blockers
艹 Potent efficacy on the heart and the vessels
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B. Calcium channel blockers
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B. Drugs affecting ion channels in CVS Potassium channel modulators
Potassium channel blockers Sulfonylureas: for treatment of diabetes Drugs under research Potassium channel openers nicorandil (尼可地尔), pinacidil (吡那地尔), cromakalim (克罗卡林) Effects are similar to calcium channel blockers
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B. Drugs affecting ion channels in CVS Sodium channel blockers
Local anesthetics Antiarrythmic drugs (class I)
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