Table 1.

Fit parameters for potentiation in the presence and absence of 3β-hydroxysteroids

	EC50(μm)		Hill n		% Potentiation	% Reduction	# Cells
	Potentiator alone	+ 3β steroid	Potentiator alone	+ 3β steroid	10 μm potentiator alone ± SEM	10 μmpotentiator + 10 μm 3β steroid*
3α5αP versus 3β5αP	2.5	2.0	1.1	0.9	1033  ± 56	−38.3	11
3α5αP versus 3β5βTHDOC	2.3	3.0	1.0	0.7	992  ± 64	−42.1	9
3α5αP versus 3β5βP	3.7	3.5	1.2	1.0	779  ± 205	−42.6	6
3α5βP versus 3β5βTHDOC	2.5	1.7	1.0	1.1	1021  ± 61	−41.9	8
3α5βTHDOC versus 3β5βTHDOC	3.0	2.1	1.3	1.3	629  ± 22	−29.4	8
3α5αTHDOC versus 3β5βTHDOC	3.2	2.6	1.6	1.2	1003  ± 49	−43.4	10
3α5αP versus 3β5αPS	3.0	2.2	1.2	1.2	854  ± 117	−38.5*	6

In experiments in which data were fit to the Hill equation, GABA was present at 2 μm, and 3β-hydroxysteroids, when present, were used at 10 μm. Percentage of potentiation was calculated by comparing the current in response to 2 μm GABA alone with the current in the presence of 2 μm GABA plus 10 μm 3α-hydroxysteroid. Reduction was calculated by comparing the size of the current in the presence of 10 μm potentiator alone with the current amplitude in the presence of equimolar concentrations (10 μm) of potentiator and 3β-hydroxysteroid.

^*indicates that 3β5αPS was used at 300 nm instead of 10 μm because of its greater potency compared with 3β-hydroxysteroids.