Direct evidence for calcium conductance of hyperpolarization-activated cyclic nucleotide-gated channels and human native I_f at physiological calcium concentrations

摘要

Aims The hyperpolarization-activated cyclic nucleotide-gated (HCN) current I_f/I_HCN is generally thought to be carried by Na+ and K+ under physiological conditions. Recently, Ca2+ influx through HCN channels has indirectly been postulated. However, direct functional evidence of Ca2+ permeation through I_f/I_HCN is still lacking.