MECHANISM OF INHIBITION OF N-METHYL-D-ASPARTATE-STIMULATED INCREASES IN FREE INTRACELLULAR CA2+ CONCENTRATION BY ETHANOL
MECHANISM OF INHIBITION OF N-METHYL-D-ASPARTATE-STIMULATED INCREASES IN FREE INTRACELLULAR CA2+ CONCENTRATION BY ETHANOL
复制标题
DOI：
10.1111/j.1471-4159.1991.tb02048.x
复制
发表时间：
1991-05-01
影响因子：
4.7
通讯作者：
LESLIE, SW
中科院分区：
文献类型：
--
作者：
DILDYMAYFIELD, JE;LESLIE, SW
从新生大鼠幼崽中分离出分离的脑细胞，并加载 fura-2。这些细胞对低 N-甲基-D-天冬氨酸 (NMDA) 浓度敏感，在不存在 Mg2+ 的情况下测量，NMDA 诱导的细胞内 Ca2+ 浓度 ([Ca2+])i) 的 EC50 值增加约 7-16-mu-M。当细胞在添加 NMDA 之前用 15 mM KCl 预去极化时，可以在含有 Mg2+ 的缓冲液中观察到 NMDA 刺激的 [Ca2+]i 增加。在这些预去极化条件下，100 mM 乙醇将 25-mu-M NMDA 反应抑制约 50%，这与在未添加 Mg2+ 的缓冲液中观察到的乙醇抑制相似。添加 NMDA 之前乙醇不会改变 [Ca2+]i。在不存在 Mg2+ 的情况下，50 和 100 mM 乙醇不会显着改变 NMDA 的 EC50 值，但在 4、16、64 和 256-mu-M NMDA 时确实以浓度依赖性方式抑制 NMDA 诱导的 [Ca2+]i 增加。虽然 NMDA 诱导的 [Ca2+]i 增加依赖于细胞外 Ca2+ 并被 Mg2+ 抑制，但 100 mM 乙醇抑制 25 mu-M NMDA 反应的能力与外部 Ca2+ 或 Mg2+ 浓度无关。甘氨酸（1、10 和 100-mu-M）可使 25-mu-M NMDA 诱导的 [Ca2+]i 增加约 50%。甘氨酸 (1-100-mu-M) 可阻止在不存在外源甘氨酸的情况下观察到的 100 mM 乙醇对 NMDA 刺激的 [Ca2+]i 的抑制作用。 MK-801 (25-400 nM) 以浓度依赖性方式抑制 25-mu-M NMDA 刺激的 [Ca2+]i 升高。与用 Mg2+ 加乙醇观察到的附加抑制不同，当 MK-801 的浓度增加到 50 nM 以上时，与单独的 MK-801 相比，乙醇（100 mM）不会对 NMDA 反应产生进一步的抑制。这些结果表明，乙醇可能对离解脑细胞中 NMDA 刺激的 Ca2+ 流入产生非竞争性抑制，与 NMDA 受体复合物上的甘氨酸以及可能的苯环己哌啶位点相互作用。
Dissociated brain cells were isolated from newborn rat pups and loaded with fura-2. These cells were sensitive to low N-methyl-D-aspartate (NMDA) concentrations with EC50 values for NMDA-induced intracellular Ca2+ concentration ([Ca2+])i) increases of approximately 7-16-mu-M measured in the absence of Mg2+. NMDA-stimulated [Ca2+]i increases could be observed in buffer with Mg2+ when the cells were predepolarized with 15 mM KCl prior to NMDA addition. Under these predepolarized conditions, 100 mM ethanol inhibited 25-mu-M NMDA responses by approximately 50%, which was similar to the ethanol inhibition observed in buffer without added Mg2+. Ethanol did not alter [Ca2+]i prior to NMDA addition. In the absence of Mg2+, 50 and 100 mM ethanol did not significantly alter the EC50 value for NMDA, but did inhibit NMDA-induced increases in [Ca2+]i in a concentration-dependent manner at 4, 16, 64, and 256-mu-M NMDA. Whereas NMDA-induced increases in [Ca2+]i were dependent on extracellular Ca2+ and were inhibited by Mg2+, the ability of 100 mM ethanol to inhibit 25 mu-M NMDA responses was independent of the external Ca2+ or Mg2+ concentrations. Glycine (1, 10, and 100-mu-M) enhanced 25-mu-M NMDA-induced increases in [Ca2+]i by approximately 50%. Glycine (1-100-mu-M) prevented the 100 mM ethanol inhibition of NMDA-stimulated [Ca2+]i observed in the absence of exogenous glycine. MK-801 (25-400 nM) inhibited 25-mu-M NMDA-stimulated rises in [Ca2+]i in a concentration-dependent manner. Unlike the additive inhibition observed with Mg2+ plus ethanol, as the concentration of MK-801 increased above 50 nM, ethanol (at 100 mM) did not produce further inhibition of NMDA responses compared with MK-801 alone. These results suggest that ethanol may produce a noncompetitive inhibition of NMDA-stimulated Ca2+ influx in dissociated brain cells, with interactions at the glycine and possibly the phencyclidine site on the NMDA-receptor complex.