Miller G W, Schnellmann R G
Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens 30602-7389.
Life Sci. 1994;55(1):27-34. doi: 10.1016/0024-3205(94)90078-7.
The neutral amino acid glycine has been demonstrated to prevent cell death in numerous cell types exposed to a variety of toxic insults. Recently, the central nervous system (CNS) glycine antagonist strychnine was demonstrated to bind specifically to the plasma membrane of renal proximal tubules (RPT) and mimic glycine cytoprotection. Further, it has been demonstrated in RPT that glycine and strychnine block chloride influx in the late stages of cell injury. The aim of this study was to determine if the RPT cytoprotective site is related to neuronal glycine receptors. Only antagonists to the CNS strychnine-sensitive glycine receptor (strychnine, brucine), and not antagonists to the glycine modulatory site of the NMDA receptor (DCQX, 7-CKA, HA-966) or the GABAA receptor (bicuculline methiodide, picrotoxin), prevented mitochondrial inhibitor (antimycin A)-induced RPT cell death. Using immunoblot analysis, proteins corresponding to the 58 kDa beta-subunit of the strychnine-sensitive glycine receptor and the associated protein gephyrin were identified in rabbit kidney cortical membrane fractions and RPT. No protein corresponding to the 48 kDa alpha-subunit was identified. Thus, glycine and strychnine may exert their cytoprotective effects via a putative plasma membrane receptor that is related to the strychnine-sensitive glycine receptor found in the CNS.
已证实中性氨基酸甘氨酸可防止多种细胞类型在遭受各种毒性损伤时发生细胞死亡。最近，中枢神经系统（CNS）甘氨酸拮抗剂士的宁被证明可特异性结合肾近端小管（RPT）的质膜，并模拟甘氨酸的细胞保护作用。此外，在RPT中已证实，甘氨酸和士的宁在细胞损伤后期可阻断氯离子内流。本研究的目的是确定RPT细胞保护位点是否与神经元甘氨酸受体有关。只有中枢神经系统士的宁敏感甘氨酸受体的拮抗剂（士的宁、马钱子碱），而不是N-甲基-D-天冬氨酸受体（DCQX、7-CKA、HA-966）或γ-氨基丁酸A型受体（荷包牡丹碱甲碘化物、印防己毒素）的甘氨酸调节位点的拮抗剂，可预防线粒体抑制剂（抗霉素A）诱导的RPT细胞死亡。通过免疫印迹分析，在兔肾皮质膜组分和RPT中鉴定出了与士的宁敏感甘氨酸受体的58 kDaβ亚基及相关蛋白桥连蛋白相对应的蛋白质。未鉴定出与48 kDaα亚基相对应的蛋白质。因此，甘氨酸和士的宁可能通过一种假定的质膜受体发挥其细胞保护作用，该受体与中枢神经系统中发现的士的宁敏感甘氨酸受体有关。
