Fucile Sergio, Renzi Massimiliano, Lax Pedro, Eusebi Fabrizio
Istituto di Fisiologia Umana, Università di Roma "La Sapienza", P le Aldo Moro 5, I-00185 Rome, Italy.
Cell Calcium. 2003 Aug;34(2):205-9. doi: 10.1016/s0143-4160(03)00071-x.
The neuronal alpha7 nicotinic acetylcholine (ACh) receptor is believed to be a highly Ca(2+) permeable ligand-gated receptor-channel. However, the contribution of Ca(2+) to cationic current generated by ACh has not yet been directly measured to date. Simultaneous fluorescence and whole-cell current measurements using the Ca(2+) indicator dye fura-2 were made in GH4C1 pituitary cells stably expressing human alpha7 receptors and the fractional Ca(2+) current (the proportion of whole-cell current carried by Ca(2+); P(f)) was determined. We report that the P(f) value was 11.4+/-1.3%. This value was significantly larger than P(f) of human L248Talpha7 receptor mutant (P(f)=6.3+/-1.0%) and of rat alpha7 receptor (P(f)=8.8+/-1.5%) both determined in transiently transfected GH4C1 cells. In our knowledge, the findings here reported indicate the human alpha7 receptors are the most Ca(2+) conductive homomeric ligand-gated receptor-channels expressed in a heterologous cell system.
神经元α7烟碱型乙酰胆碱（ACh）受体被认为是一种高度Ca(2+)通透的配体门控受体通道。然而，迄今为止，Ca(2+)对ACh产生的阳离子电流的贡献尚未得到直接测量。在稳定表达人α7受体的GH4C1垂体细胞中，使用Ca(2+)指示剂染料fura-2进行了同步荧光和全细胞电流测量，并测定了Ca(2+)电流分数（由Ca(2+)携带的全细胞电流比例；P(f)）。我们报告P(f)值为11.4±1.3%。该值显著大于在瞬时转染的GH4C1细胞中测定的人L248Tα7受体突变体的P(f)（P(f)=6.3±1.0%）和大鼠α7受体的P(f)（P(f)=8.8±1.5%）。据我们所知，此处报道的结果表明人α7受体是在异源细胞系统中表达的最具Ca(2+)传导性的同聚配体门控受体通道。
