Table 3

Voltage-dependent block of NR1/NR2A receptors by N1-OsSpm

Subunit combinationIC50 at −70 mVnH No. of oocytesKd (0)3-a3-aNo. of oocytes
μm μm
Wild-type NR1/NR2A0.72  ± 0.111.0  ± 0.16882  ± 2192.57  ± 0.0710
NR1(N616Q)/NR2A6.1  ± 0.83-b 0.9  ± 0.15567  ± 731.57  ± 0.053-b 8
NR1(N616G)/NR2A0.93  ± 0.201.0  ± 0.18670  ± 2452.76  ± 0.146
NR1/NR2A(N615G)0.10  ± 0.013-b 0.8  ± 0.1657  ± 193-b 2.47  ± 0.137
  • 3-a Values for Kd (0) and zδ were determined using text eq. 2 with data from voltage ramps (−100 to +40 mV over 6 or 12 sec), using data from the part of the I-V relationship that showed a steep voltage dependence, usually from −10 or −20 mV to −50 or −80 mV but before the recovery from block seen at very negative membrane potentials due to permeation of N1-OsSpm. The concentrations of N1-OsSpm that were used were 3 μm for wild-type NR1/NR2A, NR1(N616G)/NR2A, and NR1/NR2A(N615G) and 30 μm for NR1(N616Q)/NR2A. Although 3 μm N1-OsSpm causes only a weak block at NR1(N616Q)/NR2A channels, we also tested this concentration of N1-OsSpm in some experiments with NR1(N616Q)/NR2A. The values of Kd (0) and zδ determined in those experiments were 570 ± 337 μmand 1.62 ± 0.13, respectively (mean ± standard error, 5 oocytes), which are similar to the values obtained using 30 μm N1-OsSpm at NR1(N616Q)/NR2A channels.

  • 3-b p < 0.01 compared with wild-type NR1/NR2A (one-way ANOVA with post hoc Dunnett’s test).