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Calcium Channel Blockers － C alcium Antagonists

Calcium Channel Blockers － C alcium Antagonists. Selectively affect voltage-dependent calcium channels, inhibiting Ca 2+ entering into cells. Voltage-dependent calcium channels are classified into 6 subtypes ：. 〔Classification〕 Selective calcium channel blockers:

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Calcium Channel Blockers － C alcium Antagonists

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  1. Calcium Channel Blockers－ Calcium Antagonists Selectively affect voltage-dependent calcium channels, inhibiting Ca2+ entering into cells.

  2. Voltage-dependent calcium channels are classified into 6 subtypes：

  3. 〔Classification〕 Selective calcium channel blockers: Ⅰ Phenylalkylamines: Verapamil Ⅱ Dihydropyridines:Nifedipine Ⅲ Benzothiazepines:Diltiazem Non-selectivecalcium channel blockers: Ⅳ Flunarizine Ⅴ Prenylamine Ⅵ Others: Perhexiline

  4. Ⅰ Selective effects on L-type calcium channels，including 4 subcategories： ⅠaDihydropyridines:nifeidipine、nicardipine 、nitrendipine（尼群地平）、amlodipine（氨氯地平）、nimodipine ⅠbDiltiazem：diltiazem （地尔硫卓）、clentiazem（克仑硫卓） ⅠcPhenylalkylamines:verapamil ⅠdTiapamil：tiapamil（噻烷丙胺）

  5. Ⅱ Selective effects on other voltage-dependent calcium channels： (1) T type:Mibefradil （咪拉地尔） (2) N type: Conotoxin（竽螺毒素） (3) P type: Spider toxin（蜘蛛毒素） Ⅲ Non-selective calcium channel blockers: Prenylamine（普尼拉明） Flunarizine（氟苯桂嗪）

  6. Generations: First ：Verapamil, Nifedipine, Diltiazem Second：Nimodipine尼莫地平, Nicardipine尼卡地平, Felodipine非洛地平 Third ：Pranidipine普拉地平，Amlodipine氨氯地平

  7. L and T type are the main types in cardiovascular system, and L type is the most important one, which involves mainly in the contraction ofcardiac and smooth muscle, sinuatrial node pacing窦房结率, and atrioventricular conduction房室间传导.

  8. I II III IV Out In 6 IV III 5 5 IV III 6 II I The 1C subunit of the L-type Ca2+ channel is the pore-forming subunit Extracellular

  9. a2 a1C NH3+ COO- I II III IV NH3+ COO- d COO- NH3+ b NH3+ COO- The expression and function of the 1C subunit is modulated by other smaller subunits

  10. Action Mode Resting State Open State A A I I A I Inactive State A: Activation Gate I: Inactivation Gate

  11. 0 4 3 Cardiac cells rely on L-type Ca2+ channels for the upstroke of the AP in slow response cells Ca2+ Calcium Channel Blockers L-Type Ca2+ Slow Response Cells (SA node, AV node)

  12. Actions • Heart • negative inotropic effect负性肌力作用 • negativefrequency负性频率 and negativeconduction负性传导作用： obvious in sino-atrial node and atrioventricular node -rationale for treating supraventricular arrhythmia

  13. smooth muscle blood vessel：dilate A>V; obvious for spasmodic blood vessel; dilate coronary vessels冠状血管 other smooth muscle: relax • anti-artherosclerosis抗动脉粥样硬化作用 relieve vein wall injury caused by calcium overload increase compliance of vessel wall inhibit lipid peroxidation and protect endothelial cell

  14. nifedipine increases intracellular cAMP, leading to a decrease of intracellular cholesterin • RBC: relieve injury of RBC caused by calcium overload Inhibition of plateletactivation • Kidney: exclude sodium and diuresis

  15. Threapeutic uses • angina: effective for all kinds • arrhythmia：especially caused by supraventricular and after-depolarization triggered activity后除极触发活动 • hypertension • cerebrovascular disease • peripheral angiospasm, prophylaxis of artherosclerosis, bronchial asthma, brow ache

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