【摘要】 采用果蝇头部粗制膜烟碱乙酰胆碱受体（ｎＡｃｈＲ）与放射性配基￣（１２５）Ｉ标记的ａ一银环蛇毒素（ａ一ＢＧＴ）进行饱和结合试验，结果表明果蝇头部ｎＡｃｈＲ的数量（Ｂ＿（ｍａｘ））随增龄而减少，２０日龄和３０日龄与１日龄相比，受体数量分别从４００ｆｍｏｌ／ｍｇ下降至２９０ｆｍｏｌ／ｍｇ和２６０ｆｍｏｌ／ｍｇ，下降幅度为２７．５％和３５．０％，差异显著（Ｐ＜０．０５），但ｎＡｃｈＲ的结合能力（Ｋ＿Ｄ）不因增龄而改变，中华麦饭石对果蝇头部ｎＡｃｈＲ随龄而减少具有对抗作用，３０日龄与１日龄相比．受体数量仅从３９５ｆｍｏｌ／ｍｇ下降至３４０ｆｍｏｌ／ｍｇ，下降幅度仅为１３９％，与同日龄对照组相比，表现出明显地延缓头部ｎＡｃｈＲ数量下降的作用，中华麦饭石对Ｋ＿Ｄ值无影响。更多还原

【Abstract】 Equilibrium dissociation constant（K_D）and apparent maximum of binding sites(B_maxfor radioactivelabelled ligand￣（125）I一a一BGT and Drosophila melanogaster head nicotinic acetylcholine receptor （nAchR） were determined by saturation test experiments. An age一related decline of B_max wasfound during aging.B_max decreased from 400fmol/mg of 1 day old flies to 290 fmol/mg of 20days fiies and 260 fmol/mg of 30 days flies,the reduction rates were 27.5% and 35.0%（P<0.05）respectively.No change of K_D was detected .China Medical Stone antagonized the reduction of the B_maxin aged flies. B_max declined from 395 fmol/mg of 1 day old fliesto 340 fmol/mg of 30 days flies,the reduction rate was 13.9% only.The difTerence between theB_maxvalues of the same days aged flies with or without exposure to China Medical Stone alsodemonstrated that China Medical Stone has a significant antagonisic action on the reduction of the receptors number during aging.China Medical Stone had no effect on the K_D value of nAchR.更多还原