From: The photocurrent response of human cones is fast and monophasic
Parameter | Description | Generic macaque cone [3] | Human cone (Fig. 2) | Ground squirrel (Fig. 3) | Units |
---|---|---|---|---|---|
Ï„R | Time constant of R* inactivation | 3.4 | 3.4 | 3.0 | ms |
Ï„E | Time constant of E* inactivation | 8.7 | 9.6 | 13 | ms |
Ï„D | Time constant of cGMP hydrolysis in darkness | 360 | 360 | 60 | ms |
k β | Coupling gain from light intensity to rate of hydrolysis of cGMP | 1.6·10-4 | 10-4 |  | (ms)-1 td-1 |
 |  |  |  | 2.1·10-7 | (ms)-1 (isom/s)-1 |
n X | Apparent Hill coefficient of CNG channel activation | 1 | 1 | 1.7 | - |
Ï„Ca | Time constant of Ca2+ extrusion | 3 | 3 | 4.8 | ms |
n cyc | Hill coefficient of GC activation | 4 | 4 | 3.2 | - |
a cyc | Scaling constant of GC activation | 9·10-2 | 9·10-2 | 3.7·10-2 | - |
Ï„m | Outer segment capacitive time constant | < 4 | 2.3 | 2.3 | ms |
t delay | Delay time | < 3 | 1.3 | 2.2 | ms |