Target type: molecularfunction
Enables the transmembrane transfer of a potassium ion by a voltage-gated channel through the plasma membrane of an SA node cell contributing to the repolarization phase of an action potential. A voltage-gated channel is a channel whose open state is dependent on the voltage across the membrane in which it is embedded. [GOC:BHF, GOC:mtg_cardiac_conduct_nov11]
Voltage-gated potassium channels (Kv channels) play a crucial role in repolarizing the action potential of sinoatrial (SA) node cells, the pacemaker cells of the heart. These channels are activated by membrane depolarization, allowing potassium ions (K+) to flow out of the cell, thereby counteracting the inward sodium (Na+) current that initiated depolarization.
Specifically, in SA node cells, the delayed rectifier potassium current (IKr) mediated by Kv1.5 channels is responsible for the rapid repolarization phase of the action potential. As the cell depolarizes, Kv1.5 channels open, allowing K+ to efflux, bringing the membrane potential back towards its resting level. This rapid repolarization is essential for maintaining the normal rhythm and rate of the heart.
Another type of potassium channel, the inward rectifier potassium current (IK1), contributes to the plateau phase of the SA node action potential. These channels are active at negative membrane potentials and allow K+ to flow inward, counteracting the outward Na+ current and contributing to the relatively long plateau phase.
During the repolarization phase, the inactivation of voltage-gated sodium channels and the activation of Kv channels combine to restore the membrane potential to its resting state, preparing the SA node cell for the next action potential. This process ensures that the heart beats at a regular and efficient rhythm.
The precise timing and magnitude of K+ channel activity in SA node cells are critical for regulating heart rate. Changes in the expression or function of these channels can lead to cardiac arrhythmias, highlighting their importance in maintaining normal heart rhythm.'
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| Protein | Definition | Taxonomy |
|---|---|---|
| Potassium voltage-gated channel subfamily A member 5 | A voltage-gated potassium channel subunit KCNA5 that is encoded in the genome of human. [] | Homo sapiens (human) |
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| N-(2-aminoethyl)-5-chloro-1-naphthalenesulfonamide | naphthalenes; sulfonic acid derivative | ||
| 5-methoxypsoralen | 5-methoxypsoralen : A 5-methoxyfurocoumarin that is psoralen substituted by a methoxy group at position 5. 5-Methoxypsoralen: A linear furanocoumarin that has phototoxic and anti-inflammatory properties, with effects similar to METHOXSALEN. It is used in PUVA THERAPY for the treatment of PSORIASIS. | 5-methoxyfurocoumarin; organic heterotricyclic compound; psoralens | hepatoprotective agent; plant metabolite |
| flecainide | flecainide : A monocarboxylic acid amide obtained by formal condensation of the carboxy group of 2,5-bis(2,2,2-trifluoroethoxy)benzoic acid with the primary amino group of piperidin-2-ylmethylamine. An antiarrhythmic agent used (in the form of its acetate salt) to prevent and treat tachyarrhythmia (abnormal fast rhythm of the heart). Flecainide: A potent anti-arrhythmia agent, effective in a wide range of ventricular and atrial ARRHYTHMIAS and TACHYCARDIAS. | aromatic ether; monocarboxylic acid amide; organofluorine compound; piperidines | anti-arrhythmia drug |
| lidocaine | lidocaine : The monocarboxylic acid amide resulting from the formal condensation of N,N-diethylglycine with 2,6-dimethylaniline. Lidocaine: A local anesthetic and cardiac depressant used as an antiarrhythmia agent. Its actions are more intense and its effects more prolonged than those of PROCAINE but its duration of action is shorter than that of BUPIVACAINE or PRILOCAINE. | benzenes; monocarboxylic acid amide; tertiary amino compound | anti-arrhythmia drug; drug allergen; environmental contaminant; local anaesthetic; xenobiotic |
| nifedipine | Nifedipine: A potent vasodilator agent with calcium antagonistic action. It is a useful anti-anginal agent that also lowers blood pressure. | C-nitro compound; dihydropyridine; methyl ester | calcium channel blocker; human metabolite; tocolytic agent; vasodilator agent |
| sertindole | sertindole : A phenylindole that is 1H-indole which is substituted on the nitrogen by a p-chlorophenyl group, at position 5 by chlorine, and at position 3 by a piperidin-4-yl group, which is itself substituted on the nitrogen by a 2-(2-oxoimidazolidin-1-yl)ethyl group. | heteroarylpiperidine; imidazolidinone; organochlorine compound; organofluorine compound; phenylindole | alpha-adrenergic antagonist; H1-receptor antagonist; second generation antipsychotic; serotonergic antagonist |
| 4'-methoxyflavone | 4'-methoxyflavone: from seeds of Psoralea corylifolia (Fabaceae); structure in first source | ether; flavonoids | |
| senicapoc | senicapoc: a Gardos channel blocker; structure in first source | ||
| quinidine | quinidine : A cinchona alkaloid consisting of cinchonine with the hydrogen at the 6-position of the quinoline ring substituted by methoxy. Quinidine: An optical isomer of quinine, extracted from the bark of the CHINCHONA tree and similar plant species. This alkaloid dampens the excitability of cardiac and skeletal muscles by blocking sodium and potassium currents across cellular membranes. It prolongs cellular ACTION POTENTIALS, and decreases automaticity. Quinidine also blocks muscarinic and alpha-adrenergic neurotransmission. | cinchona alkaloid | alpha-adrenergic antagonist; anti-arrhythmia drug; antimalarial; drug allergen; EC 1.14.13.181 (13-deoxydaunorubicin hydroxylase) inhibitor; EC 3.6.3.44 (xenobiotic-transporting ATPase) inhibitor; muscarinic antagonist; P450 inhibitor; potassium channel blocker; sodium channel blocker |
| (2'-(benzyloxycarbonylaminomethyl)biphenyl-2-carboxylic acid 2-(2-pyridyl)ethylamide) | biphenyls | ||
| acacetin | 5,7-dihydroxy-4'-methoxyflavone : A monomethoxyflavone that is the 4'-methyl ether derivative of apigenin. | dihydroxyflavone; monomethoxyflavone | anticonvulsant; plant metabolite |
| clathrodin | clathrodin: structure given in first source; isolated from marine sponges of the genus Agelas | ||
| oroidin | oroidin: from marine sponges of the genus Agelas; structure in first source | pyrroles; secondary carboxamide | metabolite |
| hymenidin | hymenidin: serotonergic receptor antagonist from Okinawan marine sponge Hymeniacidon; structure given in first source | ||
| a 1899 | A 1899: a TASK-1 potassium channel blocker; structure in first source | ||
| [[(1S,2S,5R)-5-methyl-2-propan-2-ylcyclohexyl]-phenylphosphoryl]benzene | monoterpenoid |