TABLE 1.
Model parameters | Oocyte | HEK Cell | Experimental |
---|---|---|---|
α (s−1) | 0.31 | 0.16 | – |
β (s−1) | 3.6 | 9.83 | – |
Kon (μM−1s−1) | 0.096 | 0.32 | – |
Koff (s−1) | 0.18 | 4.59 | – |
EC50 (μM) | 0.80 | 2.15 | 2.11 ± 0.15 |
Slope | 2.37 | 2.09 | 2.08 ± 0.10 |
τdeact (s) at 1 μM | 26.4 | 10.7 | 11.0 ± 0.44 |
τact (s) at 1 μM* | 5.83 | 6.46 | 5.9 ± 0.45 |
10–90% rise time (s) | 12.8 | 14.2 | 13.0 ± 2.30 |
τact (s) at 30 μM* | 0.55 | 0.18 | 0.16 ± 0.01 |
10–90% rise time (s) | 1.2 | 0.4 | 0.38 ± 0.05 |
The parameters for the receptors expressed in oocytes system were taken from Chang and Weiss (4), but the calculations were done with our software implementation.
The activation kinetics is clearly complex, demonstrating a sigmoidal activation as expected for a channel with multiple cascading states; therefore, the monoexponential fit listed is only an approximation of the true activation kinetics, which in theory is always a sum of four exponentials with time constants corresponding to the inverse of the nonzero eigenvalues of the Q-matrix. The 10–90% rise time was determined from the sum of four exponentials.