TABLE 4.
Effects of mutations on GABA receptor pharmacology
The first column shows the receptor composition. The second and third columns show the ability of two compounds to enhance the response to GABA. Responses were elicited with a saturating concentration of GABA (50 μM) in the absence and presence of the potentiators 3α5αP and PEB and the ratio of the responses computed. The final column shows the relative ability of PEB to activate the receptor compared with the maximal response to GABA. This was determined from the ratio of the peak “tail” response to 1 mM PEB (see Fig. 3) to the peak response to 50 μM GABA in the same cell. The significance of differences to wild-type receptors was assessed by analysis of variance with Dunnett's post hoc correction. No results were significantly different. Data are shown as mean ± S.E. (no. of cells).
| Receptor | Potentiation by 1 μM 3α5αP | Potentiation by 100 μM PEB | Activation by 1 mM PEB |
|---|---|---|---|
| α4-β2-δ | 6.7 ± 0.7 (7) | 4.8 ± 0.6 (7) | 5.2 ± 1.1 (7) |
| α4(B)-β2-δ | 8.9 ± 2.1 (8) | 7.2 ± 1.2 (7) | 8.3 ± 2.2 (9) |
| α4(AB)-β2-δ | 8.5 ± 1.5 (5) | 5.6 ± 1.6 (6) | 3.9 ± 0.7 (6) |
| α4(C)-β2-δ | 4.9 ± 0.9 (6) | 6.1 ± 1.3 (6) | 6.0 ± 1.3 (6) |
| α4-β2-δ(B) | 8.3 ± 2.2 (6) | 5.5 ± 1.3 (6) | 4.7 ± 1.1 (7) |
| α4-β2-δ(C) | 10.1 ± 1.6 (6) | 9.2 ± 1.1 (15) | 10.3 ± 1.8 (7) |
| α4(B)-β2-δ(B) | 11.0 ± 3.3 (6) | 7.7 ± 2.2 (7) | 9.2 ± 3.3 (7) |
| α4(C)-β2-δ(C) | 5.8 ± 1.0 (6) | 8.2 ± 1.0 (6) | 7.7 ± 1.0 (6) |