Table 2.
Effects of GABA on membrane currents from X. laevis oocytes expressing A. pisum RDL, with maximum amplitude (Imax), EC50 and hill coefficient (nH) displayed. The Imax was obtained from the initial 250 μM GABA response measured from eggs clamped at −60 mV. Also shown are the effects of fipronil and the neonicotinoids imidacloprid (IMI), clothianidin (CLO), and thiacloprid (THI) on GABA EC50 induced membrane currents. IC50 values are shown for fipronil, as well as the fraction of response to GABA at EC50 after exposure to 100 μM neonicotinoid. All data are the mean ± SEM of 4-5 oocytes from ≥3 different frogs. [–] indicates that this value was not measured.
| Subunit | Imax (μA) | GABA | Fipronil IC50 (μM) | % of GABA Response with 100 μM: | |||
|---|---|---|---|---|---|---|---|
| EC50 (μM) | nH | IMI | CLO | THI | |||
| Apisum RDL1ad | 1.6 ± 0.6 | 23 ± 1.7 1 | 1.6 ± 0.1 | 0.64 ± 0.15 | 100 | 100 | – |
| Apisum RDL1bd | 1.4 ± 1.3 | 51 ± 9.2 1 | 2.0 ± 0.3 | 0.18 ± 0.06 2 | 100 | 100 | 55 ± 7 |
| Apisum RDL2b var 1 | 1.4 ± 1.5 | 28 ± 5.4 | 1.0 ± 0.1 | 0.72 ± 0.19 2 | – | – | 62 ± 2 |
1, 2 These GABA EC50 or fipronil IC50 values are significantly different (p < 0.05) using one-way ANOVA with Bonferroni’s multiple comparison test.