Isa T, Iino M, Itazawa S, Ozawa S
Department of Physiology, School of Medicine, Gunma University, Japan.
Neuroreport. 1995 Oct 23;6(15):2045-8. doi: 10.1097/00001756-199510010-00022.
AMPA-gated glutamate receptors with an inwardly rectifying current-voltage (I-V) relationship and substantial Ca2+ permeability are expressed in a population of cultured rat hippocampal neurones (type II neurones). The inward rectification of these AMPA receptors was gradually lost in cell-free membrane patches. The I-V relationship of the AMPA receptors displayed a slight outward rectification in most patches 10 min after excision. This loss of inward rectification was not accompanied by a change in the Ca2+ permeability. The inward rectification was maintained by applying physiological concentrations of spermine to the cytoplasmic side of patch membranes. These results indicate that some cytoplasmic factor mediates inward rectification in the Ca(2+)-permeable AMPA receptors, and that a candidate for this substance is spermine.
具有内向整流电流-电压（I-V）关系且具有显著Ca2+通透性的AMPA门控谷氨酸受体在一群培养的大鼠海马神经元（II型神经元）中表达。这些AMPA受体的内向整流在无细胞膜片中逐渐丧失。在切除后10分钟，大多数膜片中AMPA受体的I-V关系呈现轻微的外向整流。内向整流的丧失并未伴随着Ca2+通透性的改变。通过将生理浓度的精胺应用于膜片的细胞质侧来维持内向整流。这些结果表明，某些细胞质因子介导了Ca(2+)通透的AMPA受体中的内向整流，并且这种物质的一个候选者是精胺。
