Experimental observations on GABA EC50 and L
Values for EC50,GABA and L for the various receptors studied. The first column shows the composition of the receptor, and the second shows the background drug used to modify L. The third shows the EC50,GABA and the fourth the value of L. The footnotes indicate how L was determined. Values are mean ± S.E.M. for data from five or more oocytes.
| Receptor | Background Drug | EC50,GABA (µM) | Value of L |
|---|---|---|---|
| βαγ+βα | None | 34 ± 8 | 9000a |
| βαγ+βα | 5 µM Pro | 11 ± 1 | 1826 ± 904b |
| βαγ+βα | 10 µM Pro | 1.2 ± 0.1 | 37 ± 4c |
| βαγ+βα | 20 μM Pro | 0.50 ± 0.09 | 11 ± 4c |
| βαγ+βα | 1 μM ALF | 3.3 ± 0.4 | 606 ± 161c |
| βαγ+βα | 100 μM PEB | 1.1 ± 0.3 | 59 ± 16c |
| βαγ+βα | 200 μM PEB | 0.43 ± 0.04 | 23 ± 6c |
| βαγ+βα(L263S) | None | 3.0 ± 0.1 | 74 ± 9a |
| βα(L263S)γ+βα | None | 2.0 ± 0.1 | 19 ± 2a |
| βα(L263S)γ+βα(L263S) | None | 0.28 ± 0.04 | 7.3 ± 0.4a |
| β(Y143W)αγ+β(Y143W)α | None | 2.4 ± 0.2 | 141 ± 20a |
| β(Y143W)αγ+βα(L263S) | None | 0.70 ± 0.06 | 67 ± 5a |
| β(Y143W)αγ+βα | 25 μM Pro | 0.46 ± 0.06 | 7.4 ± 1.5c |
| βαγ+β(Y205S)α | none | 129 ± 16 | 9000d |
| βαγ+β(Y205S)α | 5 μM Pro | 88 ± 9 | 539 ± 119c |
| βαγ+β(Y205S)α | 10 μM Pro | 24 ± 2 | 315 ± 58c |
| βαγ+β(Y205S)α | 20 μM Pro | 8.2 ± 2.0 | 42 ± 5c |
| βαγ+β(Y205S)α | 40 μM Pro | 3.9 ± 0.5 | 11 ± 2c |
| βα(L263S)γ+β(Y205S)α | None | 6.1 ± 1.4 | 35 ± 1a |
ALF, alfaxalone; PEB, pentobarbital; Pro, propofol.
↵a Based on the effect of picrotoxin on constitutive activity.
↵b Calculated from the current response in the presence of the background drug corrected for constitutive activity.
↵c Calculated from the current response in the presence of the background drug assuming no constitutive activity.
↵d Considered to equal that of the wild-type receptor.