Data for the EC50 for propofol activation as a function of basal activity of the receptor for wild-type receptors or receptors containing mutations at the putative propofol-binding sites
The first column gives the concatemers expressed, whereas the second column gives the number of propofol-binding sites mutated. The third column gives the background drug used to change the basal activity of the receptor. The column headed EC50 gives the EC50 for propofol activation determined for that level of basal activity, and L gives the ratio Pclosed/Popen for that receptor in the presence of the listed background drug. Data are given as arithmetic mean ± S.E.M. (95% confidence limits; number of observations). In other cases, L was estimated from the current elicited by the background drug.
| Receptor | # | Background Drug | EC50 | L |
|---|---|---|---|---|
| µM | ||||
| βαγ-βα | 0 | None | 73 ± 6 (58–87; 9) | 9000a |
| βαγ-βα | 0 | 1 μM GABA | 11 ± 2 (5–16; 5) | 270 ± 74 (65–474; 5) |
| βαγ-βα | 0 | 10 μM GABA | 2.9 ± 0.4 (1.9–4.0; 5) | 6.4 ± 1.1 (3.4–9.4; 5) |
| βαγ-βα | 0 | 10 μM P4S | 4.7 ± 0.7 (2.7–6.7; 5) | 31 ± 12 (−2 to 65; 5) |
| β(Y143W)αγ-βα | 1 | None | 23 ± 1 (19–27; 5) | 3425 ± 680 (1539–5312; 5)b |
| β(Y143W)αγ-βα | 1 | 1 μM GABA | 2.8 ± 0.4 (1.7–3.9; 5) | 8.1 ± 0.8 (5.9–10.2; 5) |
| β(Y143W)αγ-βα | 1 | 3 μM GABA | 1.1 ± 0.1 (0.8–1.5; 5) | 1.3 ± 0.2 (0.9–1.8; 5) |
| βαγ-β(Y143W)α | 1 | None | 35 ± 4 (23–48; 5) | 2722 ± 540 (1223–4221; 5)b |
| βαγ-β(Y143W)α | 1 | 0.1 μM GABA | 16 ± 1 (13–19; 5) | 88 ± 13 (51–125; 5) |
| βαγ-β(Y143W)α | 1 | 1 μM GABA | 2.0 ± 0.3 (1.1–2.9; 5) | 3.7 ± 0.3 (2.8–4.6; 5) |
| β(M286W)αγ-βα | 1 | None | 44 ± 5 (31–58; 5) | 1457 ± 305 (672–2242; 6) |
| βαγ-β(M286W)α | 1 | None | 79 ± 6 (64–93; 6) | 17,083 ± 5940 (1813–32,354; 6) c |
| β(Y143W)αγ-β(Y143W)α | 2 | None | 12 ± 1 (9–14; 6) | 141 ± 20 (85–198; 5)b |
| β(Y143W+M286W)αγ-βα | 2 | None | 22 ± 4 (12–32; 5) | 155 ± 36 (69–241; 8)b |
| β(Y143W+M286W)αγ-βα | 2 | 1 μM GABA | 3.4 ± 0.2 (2.9–3.9; 5) | 6.9 ± 2.2 (0.9–13.0; 5) |
| βαγ-β(Y143W+M286W)α | 2 | None | 29 ± 2 (24–33; 5) | 123 ± 22 (68–177; 7)b |
| β(M286W)αγ-β(M286W)α | 2 | None | 107 ± 7 (89–125; 5) | 10,475 ± 1840 (6124–14,827; 8) |
| β(Y143W+M286W)αγ-β(Y143W)α | 3 | None | 12 ± 1 (9–15; 5) | 86 ± 19 (44–129; 10)b |
| β(Y143W+M286W)αγ-β(Y143W)α | 3 | 0.3 μM GABA | 6.2 ± 0.3 (5.4–6.9; 5) | 1.6 ± 0.1 (1.3–1.8; 5) |
| β(Y143W)αγ-β(Y143W+M286W)α | 3 | None | 15 ± 1 (12–18; 6) | 13 ± 3 (6–20; 5)b |
| β(Y143W+M286W)αγ-β(M286W)α | 3 | None | 43 ± 4 (33–54; 6) | 67 ± 10 (41–94; 5)b |
| β(Y143W+M286W)αγ-β(M286W)α | 3 | 1 μM GABA | 5.9 ± 0.6 (4.2–7.6; 5) | 1.1 ± 0.1 (0.9–1.3; 5) |
| β(M286W)αγ-β(Y143W+M286W)α | 3 | None | 43 ± 4 (33–53; 5) | 163 ± 27 (87–239; 5)b |
| β(Y143W+M286W)αγ-β(Y143W+M286W)α | 4 | None | 13 ± 1 (12–15; 6) | 11 ± 2 (6–16; 12)b |
| β(Y143W+M286W)αγ-β(Y143W+M286W)α | 4 | 0.03 μM GABA | 6.6 ± 0.4 (5.6–7.7; 5) | 4.2 ± 0.5 (2.8–5.6; 5) |
| β(Y143W+M286W)αγ-β(Y143W+M286W)α | 4 | 0.1 μM GABA | 3.7 ± 1.1 (−1.0 to 8.3; 3) | 1.1 ± 0.2 (0.6–1.7; 6) |
↵a L0 set to value of 9000. The Po,const for wild-type βαγ-βα receptors would give an estimate of L0 = 8676 ± 1429 (n = 8).
↵b L0 estimated from picrotoxin effect on currents in the absence of other drugs.
↵c L estimated from picrotoxin effect on a receptor additionally containing the α(L263S) mutation (see Materials and Methods).