Table 2.
Summary of pharmacological properties of wild-type and six GRIN2D variants
| Wild-type 2D | S573F | L670F | A675T | A678D | S1271L | R1313W | |
|---|---|---|---|---|---|---|---|
| Glutamate, EC50, μM (n) | 0.39 ± 0.02 (30) | 0.31 ± 0.04 (12)* | 0.12 ± 0.02 (12)*** | 0.02 ± 0.004 (12)*** | 0.03 ± 0.01 (11)*** | 0.25 ± 0.03 (12) | 0.31 ± 0.03 (12) |
| Glycine, EC50, μM (n) | 0.12 ± 0.01 (38) | 0.09 ± 0.01 (11) | 0.09 ± 0.02 (12)*** | 0.04 ± 0.005 (13)*** | 0.06 ± 0.01 (13)*** | 0.24 ± 0.02 (13)*** | 0.23 ± 0.01 (14)** |
| D-serine, EC50, μM (n) | 0.14 ± 0.01 (29) | 0.08 ± 0.005 (12)*** | 0.05 ± 0.01 (12)*** | 0.01 ± 0.002 (15)*** | 0.04 ± 0.01 (11)*** | 0.13 ± 0.01 (12) | 0.15 ± 0.02 (12) |
| I0.03 gly / I10 gly @-60 mV, (n) | 0.11 ± 0.04 (14) | NA | NA | 0.44 ± 0.04 (12)*** | 0.37 ± 0.06 (9)*** | NA | NA |
| I0.03 gly / I10 gly @ + 40 mV, (n) | 0.11 ± 0.04 (14) | NA | NA | 0.42 ± 0.07 (12)*** | 0.26 ± 0.03 (9) | NA | NA |
| Mg2+, IC50, μM (n)a | 158 ± 11 (31) | 91 ± 12 (9)* | 199 ± 0.6 (16) | 152 ± 11 (10) | 160 ± 23 (11) | 217 ± 0.8 (13) | 190 ± 0.8 (13) |
| Proton, % (n)b | 26 ± 0.7 (38) | 33 ± 1.7 (12)* | 65 ± 3.0 (13)*** | 49 ± 3.4 (8)*** | 26 ± 2.4 (10) | 25 ± 1.5 (12) | 29 ± 2.3 (11) |
| Calculated POPEN | 0.0067 ± 0.0003 (112) | 0.0016 ± 0.0002 (46)*** | 0.36 ± 0.01 (49)*** | ND | 0.20 ± 0.02 (44)*** | 0.0032 ± 0.0003 (44) | 0.0025 ± 0.0003 (40) |
| Surface/total, % (beta-lac assay) | 1 (14) | 0.60 ± 0.13 (4)** | 0.62 ± 0.09 (5)** | 0.21 ± 0.02 (6)*** | 0.35 ± 0.06 (6)*** | 0.69 ± 0.16 (6)* | 0.33 ± 0.13 (5)*** |
| Current amplitude, pA/pF | 29 ± 2.9 | 12 ± 3.6** | 21 ± 5.5 | 0.07 ± 0.03*** | 0.12 ± 0.04*** | 17 ± 2.8 | 20 ± 5.6 |
| Deactivation τW, ms | 5516 ± 255 | 4018 ± 361 | 36 869 ± 8978*** | ND | ND | 4992 ± 428 | 4933 ± 225 |
| Charge transfer, ms × pA/pF | 146 060 | 53 179 | 792 976*** | ND | ND | 86 056 | 96 335 |
| n | 16 | 10 | 10 | 15 | 14 | 9 | 12 |
| Memantine, IC50, μM (n; %)c | 2.5 ± 0.5 (19; 89) | NA | >150 (11; 11)*** | 11 ± 0.9 (12; 76)*** | 5.8 ± 0.9 (14; 81)*** | NA | NA |
| Dextromethorphan, IC50, μM (n; %)c | 5.1 ± 0.7 (18; 91) | NA | >300 (13; 28)*** | 10 ± 0.6 (21; 90)*** | 6.8 ± 0.7 (22; 94) | NA | NA |
| Dextrorphan, IC50, μM (n; %)c | 0.9 ± 0.1 (17; 92) | NA | >100 (12; 21)*** | 2.9 ± 0.2 (17; 80)*** | 1.7 ± 0.2 (17; 88) | NA | NA |
| Ketamine, IC50, μM (n; %)c | 4.5 ± 0.6 (18; 91) | NA | >2,000 (13; 14)*** | 25 ± 3.0 (13; 80)*** | 5.1 ± 0.8 (15; 89) | NA | NA |
Data were expressed as mean ± SEM, (n) is the number of cells recorded from. NA = not available; ND = not determined.
P-value was determined by one-way ANOVA with post hoc Dunnett’s multiple comparison test. *P < 0.05, **P < 0.01, ***P < 0.001 compared with wild-type GluN2D.
aHolding potential was −60 mV.
bPercentage of current remaining measured at pH 6.8 compared to pH 7.6 in presence of 100 μM glutamate and 100 μM glycine is given.
cData are ratio of current in drug to current in absence of drug, presented as mean ± SEM. (n; max inhibition % at 30 μM memantine, 100 μM dextromethorphan, 10 μM dextrorphan, and 100 μM ketamine).