s[J]. EMBO, 1999, 18(23): 2323-2329. Р Р 2 Seifert R,Scholten A, Gauss R, et al. Molecular characterization of a slowly gating human hyperpolarizationРactivated channel predominantly expressed in thalamus, heart, and testis[J]. Proc Natl Acad Sci, 1999, 96: 9391-9396. Р Р 3 Stieber J, Herrmann S, Feil S, et al. The hyperpolarizationactivated channel HCN4 is required for the generation of pacemaker action potentials in the embryonic heart[J]. Proc Natl Acad Sci, 2003, 100: 15235-15240.Р Р 4 Hofmann F, Biel M, Kuapp UB. International Union of Pharmacology. LI. Nomenclature and StructureFunction Relationships of Cyclic NucleotideRegulated Channels[J].Pharmacol Rev, 2005, 57(4): 455-462.Р Р 5 Ishii T M, Takano M, Ohmori H,et al. Determinants of activation ics in mammalian hyperpolarization