Table 2.

Effects of PTC-174 and (+)-CIQ on agonist potencies at NMDA receptor subtypes.

		glutamate EC50 (μM)	nH	n	glycine EC50 (μM)	nH	n
GluN1/2C	control	0.52 ± 0.05	1.3	6	0.24 ± 0.03	1.6	6
	+ 10 μM PTC-174	0.19 ± 0.02*	1.8	6	0.05 ± 0.00*	1.4	6
GluN1/2D	control	0.30 ± 0.01	1.7	6	0.12 ± 0.01	1.5	6
	+ 10 μM PTC-174	0.11 ± 0.01*	1.5	6	0.03 ± 0.01*	1.2	5
GluN1/2D	control	0.21 ± 0.02	1.5	6	0.16 ± 0.01	1.8	8
	+ 10 μM (+)-CIQ	0.23 ± 0.01	1.2	6	0.15 ± 0.02	1.2	6

Recombinant GluN1/2C and GluN1/2D NMDA receptor subtypes were expressed in Xenopus oocytes and concentration-response data for glutamate and glycine were measured using two-electrode voltage-clamp electrophysiology. Glutamate EC₅₀ values were generated by activating the receptors with increasing concentrations of glutamate in the continuous presence of 50 μM glycine in the absence and presence of 10 μM PTC-174 or 10 μM (+)-CIQ. Glycine EC₅₀ values were generated by activating the receptors with increasing concentrations of glycine in the continuous presence of 100 μM glutamate in the absence and presence of 10 μM PTC-174 or 10 μM (+)-CIQ. Data are presented as mean ± SEM, n_H is the Hill slope, and n is the number of oocytes used to generate the data. Statistical tests were performed using logEC₅₀ values and

^*indicates significantly different from control on the same receptor for the same agonist (P < 0.05; unpaired t-test).