TABLE 1

Potency of cyclic nucleotides on different HCN channel isoforms

EC50 is the concentration of ligand that produces a half-maximal voltage shift.

Cyclic nucleotideEC50 (μM)Isoform/TissueReferences
cAMPa0.06mHCN1 (Xenopus laevis)Wang et al. (2001)
0.10mHCN2 (Xenopus laevis)Wang et al. (2001)
0.50mHCN2 (HEK293 cells)Ludwig et al. (1998)
0.80mHCN2 (Xenopus laevis)Zagotta et al. (2003)
1.0mHCN2 (HEK293 cells)Zong et al. (2012)
0.08mHCN2 (Xenopus laevis)Xu et al. (2010)
0.24mHCN2-h4 chimera (Xenopus laevis)Xu et al. (2010)
1.53hHCN4 (HEK293 cells)Milanesi et al. (2006)
0.21Rabbit SAN myocyteDiFrancesco and Tortora (1991)
0.72SpHCN (sea urchin sperm)Kaupp and Seifert (2001)
cGMP6.0amHCN2 (HEK293 cells)Ludwig et al. (1998)
8.3amHCN2 (Xenopus laevis)Zagotta et al. (2003)
13.2ahHCN4 (HEK293 cells)Lolicato et al. (2014)
7.85aRabbit SAN myocyteDiFrancesco and Tortora (1991)
479bSpHCN (sea urchin sperm)Kaupp and Seifert (2001)
cCMPb29.0mHCN2 (HEK293 cells)Zong et al. (2012)
11.85Rabbit SAN myocyteDiFrancesco and Tortora (1991)

  • ↵a Full activator.

  • ↵b Partial activator.