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2693 pages added, reviewed or updated during the last month (last updated: 14/4/2021)


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If (funny) channels in the sino-atrial node

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  • pacemaker activity involves interplay between several ionic currents that influence spontaneous diastolic depolarisation of the sinoatrial node
    • these currents include the If current - the 'f' denotes 'funny' - called this because it had unusual properties compared with other current systems known at the time of its discovery
      • If current is carried by both sodium and potassium ions across the sarcolemma
        • the If current is inward at voltages in the diastolic range
          • activated on hyperpolarisation (within the diastolic range of voltages regularly observed in cardiac pacemaker tissue)
          • characterised by unusually low single-channel conductance and slow activation kinetics
          • directly activated by intracellular cyclic adenosine monophosphate (cAMP) - the If is not linked to cAMP-dependent phosphorylation activity and is carried by the hyperpolarisation-activated cyclic nucleotide-gated family of ion channel

Last reviewed 01/2018

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