Table 2

Summary of pharmacological properties of recombinant GABA_Areceptor isoforms

Agonist/Antagonist	αβ	αβε (evoked)	αβε (spontaneous)	αβγ	αβδ
GABA	1–16 μM^i,c	0.8^2-n–11 μM^h,i	N.A.	6–30 μM^c,k	0.2–8 μM^b,c
Diazepam	No effect	No effect	No effect	10–100 nM^2-l	No effect
+ Pentobarbital	26 μM^2-m	40 μM^2-n	N.A.	20–35 μM^2-j	S
Pentobarbital (alone)		N.A.	112 μM^2-n	50–540 μM^2-j	S
Loreclezole	∼1 μM^2-m	∼1 μM^2-n	1.0 μM^2-n	1 μM^d,e	N.P.
Lanthanum (α1)	N.P.	(+) 500 μM^2-n	N.P.	(+) 207 μM^2-a	N.P.
Lanthanum (α6)	N.P.	N.P.	N.P.	(−) 85 μM^2-a	(−) 21.8 μM^2-a
Zinc	<5 μM^f,h	32–42 μM^2-h	22 μM^2-n	>100 μM^f,h	1–5 μM^2-b
Picrotoxin	N.P.	N.P.	1.8 μM^2-n	N.P.	N.P.
Furosemide (α1)	N.P.	167 μM^2-n	N.P.	>5 mM^2-g	N.P.
Furosemide (α4)	N.P.	N.P.	N.P.	162 μM^2-g	N.P.
Furosemide (α6)	N.P.	N.P.	N.P.	6 μM^2-g	N.P.

Values represent IC₅₀ or EC₅₀ calculations for each compound, as appropriate. Where these values were dependent on subunit subtype, a range is reported.

S, sensitivity of receptor subtype to drug application; N.P., experiments were not performed; N.A., experimental conditions were not applicable to this study. Regarding the lanthanum experiments, (+) and (−) referred to lanthanum enhancement or inhibition of GABAR currents, respectively.
↵2-a Saxena et al. (1997).
↵2-b Saxena et al. (1994).
2-c Fisher et al. (1997).
2-d Donnelly et al. (1996).
2-e Wingrove et al. (1994).
2-f Draguhn et al. (1990).
↵2-g Wafford et al. (1996).
↵2-h Whiting et al. (1997).
2-i Davies et al. (1997).
↵2-j Thompson et al. (1996).
2-k Burgard et al. (1996).
↵2-l Pritchett et al. (1989).
↵2-m Neelands and Macdonald, unpublished data.
↵2-n This study.