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应用特异性标记配体〔~3H〕QNB 测定家兔心肌蕈碱型(Muscarine M)乙酰胆碱能受体。固定〔~3H〕QNB 浓度,特异性结合值随心肌膜制剂浓度(0.25～3.7mg/ml)而呈线性增加。由Scatchard 作图可得平衡解离常数Kd 为0.57±0.07nM(n=14),正常家兔心肌M 受体的最大结合值Bmax 为305±20fmol/mg 蛋白。在37℃时作动力学测定,得结合常数k_1 为0.03M~(-1)min~(-1)解离常数k_2为0.0158min~(-1)。由动力学计算所得Kd(0.53nM)与饱和曲线所得值一致。胆碱类药物东茛菪碱、阿托品、乙酰胆碱、氨甲酰胆碱、匹鲁卡品等抑制特异结合的IC_(50)分别为0.01、0.019、2.5、10、40μM。
Rabbit Muscarine M Acetylcholine Receptors were Determined by Using Specific Labeling Ligands [~ 3H] QNB. Fixed [~ 3H] QNB concentration, the specific binding value with myocardial membrane preparation concentration (0.25 ~ 3.7mg / ml) showed a linear increase. The equilibrium dissociation constant Kd was 0.57 ± 0.07nM (n = 14) by Scatchard mapping, and the maximum binding value Bmax of myocardium M receptor was 305 ± 20fmol / mg protein in normal rabbits. Kinetic determination at 37 ℃ showed that the dissociation constant k_2 was 0.0158min ~ (-1) at a binding constant k1 of 0.03M ~ (-1) min ~ (-1). Kd calculated from kinetics (0.53nM) is consistent with the value obtained from the saturation curve. The IC 50 of the choline scopolamine, atropine, acetylcholine, carbachol, pilocarpine and other specific inhibition were 0.01,0.019,2.5,10,40μM.