Table 1.

Characteristics of the hyperpolarization-activated current (I _f).

	g f (nS/pF)	E f (mV)	g f,Na : g f,K (ratio)	V 0.5 (mV)	τ−10 (ms)	τ+20 (ms)
Experimental data
DiFrancesco and Noble [70]	≈0.33	−10 to −20	—	≈−64	≈87	≈33
van Ginneken and Giles [39]	0.22 ± 0.02	−24 ± 2	—	≈−76	≈180	—
Present paper	0.22	−35	0.491	−73	71 ± 6	—
Mathematical models
DiFrancesco and Noble [70]	0.3303	−10.3	—	−64	195	18
van Ginneken and Giles [39]	0.2182	−24	—	−76	38	8
Demir et al. [76]	0.3569	−30	0.524	−80	25	25
Dokos et al. [74]	0.1595	−25	0.600	−78	151	104
Zhang et al. [75] central	0.0548	−5	1.000	−77	47	11
Zhang et al. [75] peripheral	0.2123	−5	1.000	−77	47	11
Kurata et al. [77]	0.3750	−26	0.622	−76	27	6
Sarai et al. [78]	0.5–0.6	−35	0.65–0.91	−61	10	3
Maltsev and Lakatta [66]	0.1500	−27	0.622	−76	27	6
Severi et al. [67]	0.2009	−4	1.000	−60	57	11
Present paper	0.2240	−35	0.491	−73	80	53

g _f: fully activated conductance; E _f: reversal potential; g _f,Na : g _f,K: ratio of sodium and potassium conductance; V _0.5: half-activation voltage; τ ₋₁₀ and τ ₊₂₀: time constant of deactivation at −10 and +20 mV, respectively.

Experimental data are mean ± SEM. Data of DiFrancesco and Noble [70] and van Ginneken and Giles [39] are not corrected for liquid junction potential.