sodium channel inhibitor

WordNet

1. direct the flow of; "channel information towards a broad audience" (同)canalize, canalise
2. a television station and its programs; "a satellite TV channel"; "surfing through the channels"; "they offer more than one hundred channels" (同)television channel, TV channel
3. a passage for water (or other fluids) to flow through; "the fields were crossed with irrigation channels"; "gutters carried off the rainwater into a series of channels under the street"
4. (often plural) a means of communication or access; "it must go through official channels"; "lines of communication were set up between the two firms" (同)communication channel, line
5. a path over which electrical signals can pass; "a channel is typically what you rent from a telephone company" (同)transmission channel
6. a deep and relatively narrow body of water (as in a river or a harbor or a strait linking two larger bodies) that allows the best passage for vessels; "the ship went aground in the channel"
7. limit, block, or decrease the action or function of; "inhibit the action of the enzyme"; "inhibit the rate of a chemical reaction"
8. control and refrain from showing; of emotions, desires, impulses, or behavior (同)bottle up, suppress
9. limit the range or extent of; "Contact between the young was inhibited by strict social customs"
10. a silvery soft waxy metallic element of the alkali metal group; occurs abundantly in natural compounds (especially in salt water); burns with a yellow flame and reacts violently in water; occurs in sea water and in the mineral halite (rock salt) (同)Na, atomic number 11
11. a substance that retards or stops an activity
12. official routes of communication; "you have to go through channels"

PrepTutorEJDIC

1. 〈C〉『水路』(川・湾・運河の船の通行ができる深い部分) / 〈U〉河床・川底 / 〈C〉『海峡』 / 〈C〉みぞ(groove),(道路の)水渠(すいきょ) / 《複数形で》(運搬・伝達の)正式の経路(手続き);(一般に)経路 / 〈C〉(テレビ・ラジオの)チャンネル / …‘に'水路を開く / …‘に'みぞを堀る / …'を'伝える,流す
2. 〈感情・欲望・行動・作用など〉‘を'抑制する / (…しないように)〈人〉‘を'抑制する,妨げる《+『名』+『from』+『名』(do『ing』)》
3. ソジウム,ナトリウム(金属元素;化学記号はNa)
4. 抑制する人(物) / 化学反応抑制剤

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/08/25 20:05:50」(JST)

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[Wiki en表示]

Sodium channel blockers are drugs which impair conduction of sodium ions (Na⁺) through sodium channels.

Extracellular

The following naturally-produced substances block sodium channels by binding to and occluding the extracellular pore opening of the channel:

• Alkaloid based toxins
  • Saxitoxin (STX)
  • Neosaxitoxin (NSTX)
  • Tetrodotoxin (TTX)

Intracellular

Drugs which block sodium channels by blocking from the intracellular side of the channel include:

• Local anesthetics
• Class I antiarrhythmic agents
• Various anticonvulsants

Unknown mechanism

• Calcium has been shown to block sodium channels which explains the effects of hypercalcemia and hypocalcemia.
• Caffeine has been shown to inhibit Na⁺ current in ventricular cells of guinea pigs.

Antiarrhythmic

Sodium channel blockers are used in the treatment of cardiac arrhythmia. They are classified as "Type I" in the Vaughan Williams classification.

Class I antiarrhythmic agents interfere with the (Na⁺) channel. Class I agents are grouped by their effect on the Na⁺ channel, and by their effect on cardiac action potentials. Class I agents are called Membrane Stabilizing Agents. 'Stabilizing' refers to the decrease of excitogenicity of the plasma membrane effected by these agents. A few class II agents, propranolol for example, also have a membrane stabilizing effect.

Class Ia agents

Class Ia agent decreasing V_max, thereby increasing action potential duration.

Class Ia agents block the fast sodium channel, which depresses the phase 0 depolarization (i.e. reduces V_max), which prolongs the action potential duration by slowing conduction. Agents in this class also cause decreased conductivity and increased refractoriness.

Indications for Class Ia agents are supraventricular tachycardia, ventricular tachycardia, symptomatic ventricular premature beats, and prevention of ventricular fibrillation.

Procainamide can be used to treat atrial fibrillation in the setting of Wolff-Parkinson-White syndrome, and to treat wide complex hemodynamically stable tachycardias. Oral procainamide is no longer being manufactured in the US, but intravenous formulations are still available.

While procainamide and quinidine may be used in the conversion of atrial fibrillation to normal sinus rhythm, they should only be used in conjunction with an AV node blocking agent such as digoxin or verapamil, or a beta blocker), because procainamide and quinidine can increase the conduction through the AV node and may cause 1:1 conduction of atrial fibrillation, causing an increase in the ventricular rate.

Class Ia agents include quinidine, procainamide and disopyramide.

Class Ib agents

Effect of class Ib antiarrhythmic agents on the cardiac action potential.

Class Ib antiarrhythmic agents are sodium channel blockers. They have fast onset and offset kinetics, meaning that they have little or no effect at slower heart rates, and more effects at faster heart rates. Class Ib agents shorten the action potential duration and reduce refractoriness. These agents will decrease V_max in partially depolarized cells with fast response action potentials. They either do not change the action potential duration, or they may decrease the action potential duration. Class Ib drugs tend to be more specific for voltage gated Na channels than Ia. Lidocaine in particular is highly frequency dependent, in that it has more activity with increasing heart rates. This is because lidocaine selectively blocks Na channels in their open and inactive states and has little binding capability in the resting state.

Class Ib agents are indicated for the treatment of ventricular tachycardia and symptomatic premature ventricular beats, and prevention of ventricular fibrillation.

Class Ib agents include lidocaine, mexiletine, tocainide, and phenytoin.

Class Ic agents

Effect of class Ic antiarrhythmic agent on cardiac action potential.

Class Ic antiarrhythmic agents markedly depress the phase 0 depolarization (decreasing V_max). They decrease conductivity, but have a minimal effect on the action potential duration. Of the sodium channel blocking antiarrhythmic agents (the class I antiarrhythmic agents), the class Ic agents have the most potent sodium channel blocking effects.

Class Ic agents are indicated for life-threatening ventricular tachycardia or ventricular fibrillation, and for the treatment of refractory supraventricular tachycardia (i.e. atrial fibrillation). These agents are potentially pro-arrhythmic, especially in settings of structural heart disease (e.g. post-myocardial infarction), and are contraindicated in such settings.

Class Ic agents include encainide, flecainide, moricizine, and propafenone. Encainide is not available in the United States.

Other uses

Sodium channel blockers are also used as local anesthetics and anticonvulsants.

Sodium channel blockers have been proposed for use in the treatment of cystic fibrosis, but current evidence is mixed.

It has been suggested that the analgesic effects of some antidepressants may be mediated in part via sodium channel blockade.

Future prospects

Selective blockers of Na_v1.7 and Na_v1.8 voltage-gated sodium channels, such as CNV1014802 and TV-45070, are being investigated as novel analgesics.

See also

• Sodium channel
• Conotoxin
• Raventoxin
• Halcurin

References

UpToDate Contents

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• 1. 腎集合管ナトリウムチャンネルの遺伝的障害：リドル症候群および偽性低アルドステロン症1型 genetic disorders of the collecting tubule sodium channel liddles syndrome and pseudohypoaldosteronism type 1
• 2. 低アルドステロン症（4型RTA）の病因、診断、および治療 etiology diagnosis and treatment of hypoaldosteronism type 4 rta
• 3. ブルガダ症候群および突然の心停止 brugada syndrome
• 4. 心臓の虚血性再潅流障害 ischemic reperfusion injury of the heart
• 5. 抗てんかん剤の薬理学 pharmacology of antiepileptic drugs

English Journal

• Sexual function in patients with chronic angina pectoris.

• Kloner RA, Henderson L.SourceDepartment of Medicine, Division of Cardiovascular Medicine of Keck School of Medicine and Good Samaritan Hospital, University of Southern California, Los Angeles, California. Electronic address: rkloner@goodsam.org.
• The American journal of cardiology.Am J Cardiol.2013 Jun 1;111(11):1671-6. doi: 10.1016/j.amjcard.2013.02.009. Epub 2013 Apr 2.
• Drugs for erectile dysfunction (ED) may be contraindicated with nitrates commonly used to treat patients with angina pectoris, and certain antianginal therapies may worsen ED. The American Heart Association and the Princeton Consensus Conference panel of experts recommend that patients with coronary
• PMID 23558039

• Differential mechanisms underlying neuroprotection of hydrogen sulfide donors against oxidative stress.

• Jia J, Xiao Y, Wang W, Qing L, Xu Y, Song H, Zhen X, Ao G, Alkayed NJ, Cheng J.SourceDepartment of Pharmacology, College of Pharmaceutical Sciences, Soochow University, Suzhou, China; The Second Affiliated Hospital of Soochow University, Soochow University, Suzhou, China; Institute of Neuroscience, Soochow University, Suzhou, China.
• Neurochemistry international.Neurochem Int.2013 Jun;62(8):1072-8. doi: 10.1016/j.neuint.2013.04.001. Epub 2013 Apr 12.
• This study investigated whether slow-releasing organic hydrogen sulfide donors act through the same mechanisms as those of inorganic donors to protect neurons from oxidative stress. By inducing oxidative stress in a neuronal cell line HT22 with glutamate, we investigated the protective mechanisms of
• PMID 23587562

Japanese Journal

• Scope and Limitation for FeSO4-Mediated Direct Arylation of Heteroarenes with Arylboronic Acids and Its Synthetic Applications

• Bulletin of the Chemical Society of Japan 87(2), 301-313, 2014
• NAID 130004153279

• A new experimental model of ATP-sensitive K^+ channel-independent insulinotropic action of glucose : a permissive role of cAMP for triggering of insulin release from rat pancreatic β-cells

• Endocrine journal 60(5), 599-607, 2013-05-01
• NAID 10031184527

• A new experimental model of ATP-sensitive K+ channel-independent insulinotropic action of glucose: a permissive role of cAMP for triggering of insulin release from rat pancreatic beta-cells

• ENDOCRINE JOURNAL 60(5), 599-607, 2013-05
• NAID 120005647612

Related Links

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★リンクテーブル★

関連記事	「inhibit」「channel」「inhibitor」「sodium channel」

「inhibit」

　　[★]

• v.

• 抑制する、阻害する、阻止する

関

abrogate、block、depress、depression、deter、inhibition、interdict、prevent、prevention、repress、repression、restrain、restraint、suppress、suppression

　 　 　 　

「channel」

　　[★]

• n.

• 川床、川底。水路、河道
• 海峡
• 水管、導管
• 溝
• 経路、ルート。道筋、方向

• チャネル、チャンネル、イオンチャネル

関

ion channel、ionic channel

　 　 　 　 　 　 　

「inhibitor」

　　[★]

• n.

• 阻害剤、阻害薬、抑制薬、抑制剤、(内在性物質について)インヒビター、抑制物質

関

blocker、depressant、suppressant

　 　

「sodium channel」

　　[★]

ナトリウムチャネル

関

Na channel、Na+ channel