Funny current.html
 
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Funny current (or funny channel, or If) refers to a specific current in the heart. It is called "funny" because it has effects opposite to those of most other heart currents.

If is a mixed Na+–K+ inward current activated by hyperpolarization and modulated by the autonomic nervous system. It is one of the most important ionic currents for regulating pacemaker activity in the sinoatrial (SA) node.

Most channels are activated through depolarization, but in the SA node and AV node, the channel becomes activated through hyperpolarization, at approximately -40mV.

Funny currents have been associated with cyclic-nucleotide-gated channels.1

Contents

Clinical significance

Ivabradine

Drugs such as ivabradine are intended to inhibit the funny current, and thus slow down the heart rate. Ivabradine selectively inhibits the pacemaker If current in a dose-dependent manner.

See also

References

  1. ^ DiFrancesco D (2006). "Serious workings of the funny current". Prog. Biophys. Mol. Biol. 90 (1-3): 13–25. doi:10.1016/j.pbiomolbio.2005.05.001. PMID 15975637. 

External links

  • Accili E, Proenza C, Baruscotti M, DiFrancesco D. "From funny current to HCN channels: 20 years of excitation.". News Physiol Sci 17: 32–7. PMID 11821534. 
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Membrane transport protein: ion channels
Ca2+: Calcium channel
L-type/Cavα (1.1, 1.2, 1.3, 1.4) • N-type/Cavα2.2 • P-type/Cavα(2.1) • Q-type/Cavα2.1 • R-type/Cavα2.3 • T-type/Cavα(3.2)
α2δ-subunits (1, 2) • β-subunits (β1, β2, β3, β4) • γ-subunits (γ1, γ2, γ3, γ4)
Cation channels of sperm (1, 2, 3, 4)  • Two-pore channel (1, 2)
Ligand-gated
Na+: Sodium channel
Navα (1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 7A) • Navβ (1, 2, 3, 4)
Other
K+: Potassium channel
Kvα1-6 (1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.10) • (2.1, 2.2) • (3.1, 3.2, 3.3, 3.4) • (4.1, 4.2, 4.3) • (5.1) • (6.1, 6.2, 6.3, 6.4)
Kvα7-12 (7.1, 7.2, 7.3, 7.4, 7.5) • (8.1, 8.2) • (9.1, 9.2, 9.3) • (10.1, 10.2) • (11.1/hERG, 11.2, 11.3) • (12.1, 12.2, 12.3)
Kvβ (1, 2, 3) • KCNIP (1, 2, 3, 4) • minK/ISK • minK/ISK-like • MiRP (1, 2, 3) • Shaker gene
BK channel (α1, β1, β2, β3, β4) • SK channel (SK1, SK2, SK3, SK4) • KCa (1.1, 2.1, 2.2, 2.3, 3.1, 4.1, 4.2, 5.1)
Kir (1.1, 2.1, 2.2, 2.3, 2.4) • GIRK/Kir (3.1, 3.2, 3.3, 3.4) • Kir (4.1, 4.2, 5.1, 6.1, 6.2, 7.1)
K2P (1, 2, 3, 4, 5, 6, 7, 9, 10, 12, 13, 15, 16, 17, 18)
M+: TRP cation channel
TRPA (1) • TRPC (1, 2, 3, 4, 4AP, 5, 6, 7) • TRPM (1, 2, 3, 4, 5, 6, 7, 8) • TRPML (1, 2, 3) • TRPP (1, 2) • TRPV (1, 2, 3, 4, 5, 6)
Cl-: Chloride channel
ANO1 • Bestrophin (1, 2)  • CFTR • CLCA (1, 2, 3, 4) • CLCN (1, 2, 3, 4, 5, 6, 7, KA, KB) • CLIC (1, 2, 3, 4, 5, 6, L1) • CLNS (1A, 1B)
Cyclic nucleotide-gated (FC)
α (1, 2, 3, 4) • β (1, 2, 3) • HCN (1, 2, 3, 4)
Porin
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