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Section III Circulation system.

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Presentation on theme: "Section III Circulation system."— Presentation transcript:

1 Section III Circulation system

2 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

3 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

4 Chapter 6 Cardiovascular Drugs
Part 1 Drugs affecting ion channels in CVS

5 Modes of solute transmembrane transport
ion channel Modes of solute transmembrane transport

6 A. General properties of ion channels in CVS
Permeation Selectivity Gating voltage-gated chemically gated: ligand-gated phospharylation-gated mechanosensitive nongated background / leak channels

7 Ion transmembrane transport

8 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

9 A. General properties of ion channels in CVS
Voltage-gated ion channels Na+ channels Ca2+ channels K+ channels

10 General structure of ion channels Structure of -subunit
filter voltage sensor General structure of ion channels Structure of -subunit

11 Na+ Channels K+ Channels Ca2+ Channels

12 A. General properties of ion channels in CVS
Functional regulation of voltage-gated ion channels Activation (open) Inactivation (close)

13 Gating modes of ion channels

14 Ligand-gated ion channels

15 G protein/cyclic nucleotide-gated ion channels
cyclic AMP  subunit of G protein

16 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

17 Calcium channels

18 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.

19 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

20 Binding sites of antagonists on L-type calcium channels
dihydropyridines verapamil Binding sites of antagonists on L-type calcium channels

21 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

22 Nifedipine 硝苯地平 Diltiazem 地尔硫卓 Verapamil 维拉帕米
Nifedipine 硝苯地平 Diltiazem 地尔硫卓 Verapamil 维拉帕米

23 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

24 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

25 Mechanism of calcium channel blocker on myocardial and vascular smooth muscle

26 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

27 B. Calcium channel blockers
(5) Others Kidney: increasing the blood flow of kidney Endocrine: inhibiting the release of ACTH, TSH, insulin, etc.

28 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

29 B. Calcium channel blockers
6. Clinical uses (1) Angina pectoris Variant angina: nifedipine Stable angina: verapamil, diltiazem Unstable angina: verapamil, diltiazem, nifedipine +  receptor blockers

30 B. Calcium channel blockers
(2) Arrhythmias supraventricular tachycardia arrhythmias induced by triggered activity following after-depolarization - verapamil, diltiazem

31 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.

32 B. Calcium channel blockers
(4) Cerebrovascular diseases transient ischemic attack, cerebral thrombosis, subarachnoid hemorrhage (5) Others peripheral vascular spasmodic disease, arteriosclerosis etc.

33 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)

34 B. Calcium channel blockers
8. Special agents Nifedipine 硝苯地平

35 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.

36 B. Calcium channel blockers Selectively acting on cerebral vasculature
Nimodipine 尼莫地平 Selectively acting on cerebral vasculature

37 B. Calcium channel blockers
Verapamil 维拉帕米 Potent efficacy on the heart, and weak on the vessels

38 Diltiazem 地尔硫卓 B. Calcium channel blockers
Potent efficacy on the heart and the vessels

39 B. Calcium channel blockers

40 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

41 B. Drugs affecting ion channels in CVS Sodium channel blockers
Local anesthetics Antiarrythmic drugs (class I)


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