Table 1

K_i values and exchange rates for transport inhibitors

Compound	K_i	Concentration	Exchange rate (pmol/mg protein/ 2 min)
	μM
l-Glutamate	4.9 ± 1	100	362 ± 12
		50	344 ± 16
		10	316 ± 22
2,4-MPDC	6.8 ± 3	100	282 ± 28
		75	280 ± 30
l-Aspartate	1.7 ± 0.6	100	278 ± 16
		20	266 ± 22
cis-ACBD	30 ± 2	100	266 ± 4
		300	270 ± 8
l-cis-2,4-PDC	66 ± 6	100	206 ± 16
		500	260 ± 22
l-trans-2,4-PDC	1.5 ± 0.5	100	250 ± 28
		15	208 ± 28
l-β-THA	2.0 ± 1	100	172 ± 24
		20	162 ± 16
l-trans-2,3-ADC	78 ± 6	100	146 ± 14
		800	156 ± 26
l-anti-endo-3,4-MPDC	4.9 ± 2	100	120 ± 20
		50	120 ± 18
Kainate	59 ± 6	100	0 ± 1.5
		600	0 ± 0
cis-5-Me-l-trans-2,3-PDC	37 ± 6	100	3 ± 6
		350	0 ± 0
DHK	28 ± 2	100	0 ± 3
		300	11.4 ± 6
DHK+		300	60 ± 12
l-Glutamate		10
l-trans-2,3-PDC	33 ± 6	100	3 ± 6
		300	19 ± 6
l-trans-2,3-PDC +l-Glutamate		300 10	76 ± 16

K _i values ± S.D. reported in this table represent the average of at least three separate Lineweaver-Burk analyses that were carried out as described in Figure 2. The synaptosomal efflux of d-[³H]aspartate induced by the inhibitors was quantified over a 2-min period at 37°C and was corrected for the efflux that occurred in the absence of added compound (228 ± 8 pmol/mg protein/2 min). Inhibitors were tested both at 100 μM and, to ensure comparable levels of transporter binding, at concentrations approximately 10 times greater than theK _i values for which they inhibitedd-[³H]aspartate uptake. Values represent mean ± S.E. from at least four separate determinations conducted in duplicate.