WordNet
- a three-dimensional shape with six square or rectangular sides (同)cube
- (computer science) a sector or group of sectors that function as the smallest data unit permitted; "since blocks are often defined as a single sector, the terms `block and `sector are sometimes used interchangeably"
- support, secure, or raise with a block; "block a plate for printing"; "block the wheels of a car"
- a solid piece of something (usually having flat rectangular sides); "the pyramids were built with large stone blocks"
- housing in a large building that is divided into separate units; "there is a block of classrooms in the west wing"
- a rectangular area in a city surrounded by streets and usually containing several buildings; "he lives in the next block" (同)city block
- an inability to remember or think of something you normally can do; often caused by emotional tension; "I knew his name perfectly well but I had a temporary block" (同)mental_block
- a number or quantity of related things dealt with as a unit; "he reserved a large block of seats"; "he held a large block of the companys stock"
- interrupt the normal function of by means of anesthesia; "block a nerve"; "block a muscle"
- run on a block system; "block trains"
- shape by using a block; "Block a hat"; "block a garment"
- shape into a block or blocks; "block the graphs so one can see the results clearly"
- stamp or emboss a title or design on a book with a block; "block the book cover"
- direct the flow of; "channel information towards a broad audience" (同)canalize, canalise
- 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
- 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"
- (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
- a path over which electrical signals can pass; "a channel is typically what you rent from a telephone company" (同)transmission channel
- 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"
- a light soft silver-white metallic element of the alkali metal group; oxidizes rapidly in air and reacts violently with water; is abundant in nature in combined forms occurring in sea water and in carnallite and kainite and sylvite (同)K, atomic number 19
- a class of drugs that inhibit (block) some biological process (同)blocking_agent
- a football player whose responsibility is to block players attempting to stop an offensive play
- official routes of communication; "you have to go through channels"
PrepTutorEJDIC
- (木・石などの,通例平らな面のある)『かたまり』 / 《米》(四団を街路に囲まれた)『区画』,街区 / 街区の1辺の距離(一般に40メートル前後) / 《英》ブロック(アパート・事務所・商店などに区切られている大きな建物) / 『妨害物』,障害物(obstacle);(障害によって生じた)停滞,渋滞 / 台木,台(まないた・肉切り台・まき割り台・せり売り台・帽子の木型など);《the~》炭頭台 / (特にアメリカンフットボールで)ブロック(相手の選手の突進を阻止する) / 滑車(pulley) / (座席券・株券などの)一組《+『of』+『名』》 / 〈通路など〉'を'『ふさぐ』,〈通行・進行など〉'を'妨げる / 〈帽子など〉の型取りをする / (特にアメリカンフットボールで)〈相手選手の突進〉'を'ブロックする;(ボクシングで)〈相手のパンチ〉'を'ブロックする
- 〈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
- ポタシウム,カリウム(金属元素;化学記号はK)
Wikipedia preview
出典(authority):フリー百科事典『ウィキペディア(Wikipedia)』「2013/05/04 20:49:26」(JST)
[Wiki en表示]
Potassium channel blockers are agents which interfere with conduction through potassium channels.
Contents
- 1 Arrhythmia
- 1.1 Mechanism
- 1.2 Examples and uses
- 1.3 Side effects
- 2 Anti-diabetics
- 3 Other uses
- 4 See also
- 5 References
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Arrhythmia
Effect of class III antiarrhythmic agent on cardiac action potential.
Potassium channel blockers used in the treatment of cardiac arrhythmia are classified as class III antiarrhythmic agents.
Mechanism
Class III agents predominantly block the potassium channels, thereby prolonging repolarization.[1] More specifically, their primary effect is on IKr.[2]
Since these agents do not affect the sodium channel, conduction velocity is not decreased. The prolongation of the action potential duration and refractory period, combined with the maintenance of normal conduction velocity, prevent re-entrant arrhythmias. (The re-entrant rhythm is less likely to interact with tissue that has become refractory).
Class III antiarrhythmic agents exhibit reverse use dependent prolongation of the action potential duration (Reverse use-dependence). This means that the refractoriness of the ventricular myocyte increases at lower heart rates. This increases the susceptibility of the myocardium to early after-depolarizations (EADs) at low heart rates. Antiarrhythmic agents that exhibit reverse use-dependence are more efficacious at preventing a tachyarrhythmia than converting someone into normal sinus rhythm. Because of the reverse use-dependence of class III agents, at low heart rates class III antiarrhythmic agents may paradoxically be more arrhythmogenic.
Examples and uses
- Amiodarone is indicated for the treatment of refractory VT or VF, particularly in the setting of acute ischemia. Amiodarone is also safe to use in individuals with cardiomyopathy and atrial fibrillation, to maintain normal sinus rhythm. Amiodarone prolongation of the action potential is uniform over a wide range of heart rates so this drug does not have reverse use-dependent action. Amiodarone was the first agent described in this class.[3] Amiodarone should only be used to treat adults with life-threatening ventricular arrhythmias when other treatments are ineffective or have not been tolerated. FDA MedWatch http://www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/DrugSafetyInformationforHeathcareProfessionals/ucm084108.htm
- Dofetilide blocks only the rapid K channels; this means that at higher heart rates, when there is increased involvement of the slow K channels, dofetilide has less of an action potential-prolonging effect.
- Sotalol is indicated for the treatment of atrial or ventricular tachyarrhythmias, and AV re-entrant arrhythmias.
- Ibutilide is the only antiarrhythmic agent currently approved by the Food and Drug Administration for acute conversion of atrial fibrillation to sinus rhythm.
- Ampyra (recently approved for MS)
Side effects
These agents include a risk of torsades de pointes.[5]
Anti-diabetics
Sulfonylureas come under the class of ATP-sensitive potassium channel blockers.
Other uses
Dalfampridine, A potassium channel blocker has also been approved for use in the treatment of multiple sclerosis.[6]
See also
- Potassium channel
- Potassium channel opener
References
- ^ Lenz TL, Hilleman DE (July 2000). "Dofetilide, a new class III antiarrhythmic agent". Pharmacotherapy 20 (7): 776–86. doi:10.1592/phco.20.9.776.35208. PMID 10907968.
- ^ Riera AR, Uchida AH, Ferreira C, et al. (2008). "Relationship among amiodarone, new class III antiarrhythmics, miscellaneous agents and acquired long QT syndrome". Cardiol J 15 (3): 209–19. PMID 18651412.
- ^ "Milestones in the Evolution of the Study of Arrhythmias".
- ^ Sahara M, Sagara K, Yamashita T, Iinuma H, Fu LT, Watanabe H (August 2003). "Nifekalant hydrochloride, a novel class III antiarrhythmic agent, suppressed postoperative recurrent ventricular tachycardia in a patient undergoing coronary artery bypass grafting and the Dor approach". Circ. J. 67 (8): 712–4. doi:10.1253/circj.67.712. PMID 12890916.
- ^ "Introduction: Arrhythmias and Conduction Disorders: Merck Manual Professional".
- ^ Judge SI, Bever CT (July 2006). "Potassium channel blockers in multiple sclerosis: neuronal Kv channels and effects of symptomatic treatment". Pharmacol. Ther. 111 (1): 224–59. doi:10.1016/j.pharmthera.2005.10.006. PMID 16472864.
Channel blockers
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Calcium (Ca2+) |
|
|
Potassium (K+) |
- 3,4-Diaminopyridine
- 4-Aminopyridine
- Amiodarone
- Bretylium
- Bunaftine
- Charybdotoxin
- Conotoxins
- Dofetilide
- Dronedarone
- E-4031
- Ibutilide
- Linopirdine
- Maurotoxin
- Nifekalant
- Paxilline
- Sotalol
- Tedisamil
- Tetraethylammonium
- Vernakalant
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|
Sodium (Na+) |
- Antiarrhythmics: Ajmaline
- Aprindine
- Disopyramide
- Dronedarone
- Encainide
- Flecainide
- Lidocaine
- Lorajmine
- Lorcainide
- Mexiletine
- Moricizine
- Phenytoin
- Pilsicainide
- Prajmaline
- Procainamide
- Propafenone
- Quinidine
- Sparteine
- Tocainide
- Anticonvulsants: Carbamazepine
- Eslicarbazepine acetate
- Ethotoin
- Fosphenytoin
- Licarbazepine
- Mephenytoin
- Oxcarbazepine
- Oxitriptyline
- Phenytoin
- Rufinamide
- Topiramate
- Sodium valproate
- Valnoctamide
- Valproate pivoxil
- Valproate semisodium
- Valproic acid
- Valpromide
- Diuretics: Amiloride
- Benzamil
- Triamterene
- Local anesthetics: pFBT
- Amylocaine
- Articaine
- Benzocaine
- Bupivacaine (Levobupivacaine, Ropivacaine)
- Butacaine
- Butamben
- Chloroprocaine
- Cinchocaine
- Cocaine
- Cyclomethycaine
- Dimethocaine
- Etidocaine
- Hexylcaine
- Iontocaine
- Lidocaine
- Mepivacaine
- Meprylcaine
- Metabutoxycaine
- Orthocaine
- Piperocaine
- Prilocaine
- Procaine
- Propoxycaine
- Proxymetacaine
- Risocaine
- Tetracaine
- Trimecaine
- Toxins: Conotoxins
- Neosaxitoxin
- Saxitoxin
- Tetrodotoxin
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Other |
- Uncategorized: Ethadione
- Paramethadione
- Phenacemide
- Pheneturide
- Trimethadione
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Antiarrhythmic agents (C01B)
|
|
Channel blockers |
class I
(Na+ channel blockers)
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class Ia (Phase 0→ and Phase 3→)
|
- Procainamide #
- Quinidine #
- Ajmaline
- Disopyramide
- Prajmaline
- Lorajmine
- Sparteine
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class Ib (Phase 3←)
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- IV (Lidocaine #)
- enteral (Mexiletine
- Tocainide
- Aprindine)
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class Ic (Phase 0→)
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- Encainide‡
- Flecainide
- Lorcainide
- Moracizine‡
- Propafenone
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|
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class III
(Phase 3→, K+ channel blockers)
|
- Amiodarone
- Dronedarone
- Bretylium
- Bunaftine
- Dofetilide
- Ibutilide
- Nifekalant
- Sotalol
- Tedisamil
- Vernakalant
- E-4031
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class IV
(Phase 4→, Ca2+ channel blockers)
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|
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Receptor agonists
and antagonists |
class II
(Phase 4→, β blockers)
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- Propranolol
- Nadolol
- Pindolol
- cardioselective (Atenolol
- Metoprolol
- Acebutolol
- Esmolol)
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A1 agonist
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M2
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- muscarinic antagonist: Atropine
- Quinidine
- Disopyramide
muscarinic agonist: Digoxin
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α receptors
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- Quinidine
- Verapamil
- Amiodarone
- Bretylium
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|
|
Ion transporters |
|
|
- #WHO-EM
- ‡Withdrawn from market
- Clinical trials:
- †Phase III
- §Never to phase III
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noco/cong/tumr, sysi/epon, injr
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proc, drug (C1A/1B/1C/1D), blte
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UpToDate Contents
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English Journal
- Blockade of presynaptic 4-aminopyridine-sensitive potassium channels increases initial neurotransmitter release probability, reinstates synaptic transmission altered by GABAB receptor activation in rat midbrain periaqueductal gray.
- Li G1, Liu ZL, Zhang WN, Yang K.
- Neuroreport.Neuroreport.2016 Jan 6;27(1):50-5. doi: 10.1097/WNR.0000000000000499.
- The activation of γ-aminobutyric acid receptor subtype B (GABAB) receptors in the midbrain ventrolateral periaqueductal gray (vlPAG) induces both postsynaptic and presynaptic inhibition. Whereas the postsynaptic inhibition is mediated by G protein-coupled inwardly rectifying K channels, the presyna
- PMID 26575285
- The voltage-gated potassium channel Kv1.3 is a promising multitherapeutic target against human pathologies.
- Pérez-Verdaguer M1, Capera J1, Serrano-Novillo C1, Estadella I1, Sastre D1, Felipe A1.
- Expert opinion on therapeutic targets.Expert Opin Ther Targets.2015 Dec 4:1-15. [Epub ahead of print]
- INTRODUCTION: The voltage-dependent potassium channel Kv1.3 is mainly present in the nervous and immune systems. In leukocytes, Kv1.3 fine-tunes the activation and proliferation of the immune response. However, Kv1.3 is also present in other tissues where its physiological role is still under invest
- PMID 26634786
- Insulin and IGF-1 activate Kir4.1/5.1 channels in cortical collecting duct principal cells to control basolateral membrane voltage.
- Zaika O1, Palygin O2, Tomilin V3, Mamenko M1, Staruschenko A2, Pochynyuk O4.
- American journal of physiology. Renal physiology.Am J Physiol Renal Physiol.2015 Dec 2:ajprenal.00436.2015. doi: 10.1152/ajprenal.00436.2015. [Epub ahead of print]
- Potassium Kir4.1/5.1 channels are abundantly expressed at the basolateral membrane of principal cells in the cortical collecting duct (CCD) where they are thought to modulate transport rates by controlling trans-epithelial voltage. Insulin and insulin-like growth factor-1 (IGF-1) stimulate apically
- PMID 26632606
Japanese Journal
- A Simple Protocol for the Myocardial Differentiation of Human iPS Cells
- Serofendic Acid Protects Against Myocardial Ischemia–Reperfusion Injury in Rats
- Procaine, a State-Dependent Blocker, Inhibits HERG Channels by Helix Residue Y652 and F656 in the S6 Transmembrane Domain
Related Links
- Potassium channel blocker information including symptoms, causes, diseases, symptoms, treatments, and other medical and health issues. ... Introduction: Potassium channel blocker Description of Potassium channel blocker ...
- class III potassium channel blocker drugs for treatment of arrhythmias ... Side Effects and Contraindications All of these compounds, like Class I compounds, are proarrhythmic as well as being antiarrhythmic. For example, the ...
Related Pictures
★リンクテーブル★
[★]
- 英
- potassium channel blocker
[★]
- 関
- blockade、blockage、deter、inhibit、inhibition、lump、prevent、prevention、repress、repression、seal、turn off
[★]
- 川床、川底。水路、河道
- 海峡
- 水管、導管
- 溝
- 経路、ルート。道筋、方向
- 関
- ion channel、ionic channel
[★]
- 関
- antagonist、blocking agent、inhibitor