大鼠胃粘膜胃泌素受体的放射配基结合法

目的　建立高效、敏感的大鼠胃粘膜胃泌素受体结合模型。方法　用大鼠胃粘膜粗膜标本为组织受体，［１２５Ｉ］ １５ Ｌｅｕ Ｇ １７为标记配基进行受体结合反应，检测胃泌素受体结合参数。结果　胃泌素受体结合符合简单单位点受体结合模型，Ｓｃａｔｃｈａｒｄ分析求出的胃泌素受体结合参数Ｂｍａｘ＝７－４０４×１０－１２ｍｏｌ·Ｌ－１（３－７０２ｐｍｏｌ·ｇ－１Ｐｒｏ），Ｋｄ＝１－６８６×１０－１０ｍｏｌ·Ｌ－１。单点法求出的特异结合量Ｒｓ＝２－７３４ｐｍｏｌ·ｇ－１Ｐｒｏ。粗膜标本蛋白浓度在４～１２ｇ·Ｌ－１范围内，与标记胃泌素特异性结合容量成正比。同一样本大鼠胃粘膜粗膜标本［１２５Ｉ］ ＧＡＳ特异结合量测定方法变异系数为７－８０％，竞争抑制实验证明［１２５Ｉ］ ＧＡＳ与大鼠胃粘膜粗膜标本结合特异性良好。结论　大鼠胃粘膜胃泌素受体的放射配基结合法符合受体结合实验方法学要求。

Establishment of radioligand binding assay of gastrin receptors in rats

AIM To establish radioligand binding assay of gastrin receptors in rats. METHODS The model of receptors was studied in rat gastric mucosal membrane preparations after an incubation period of 30 min at 30℃ (pH 7 4) with a protein concentration of 8～12 g·L -1 (150～200 μg per assay tube) by 125 I 15 Leu Gastrin 17 I. RESULTS The gastrin binding was shown to be saturable with a equilibrium K d of 1 686×10 -10 mol·L -1 and a Bmax of 3 702×10 -12 pmol·g -1 Pro estimated by LIGAND program. The amount of gastrin bound was strongly associated with the protein concentration of rat gastric mucosal membrane preparations ranged from 4 to 12 g·L -1 . The variant coefficent of the receptor binding assay was 7 8% within the same group. The competitive analyses showed the gastric mucosal membrane preparations was bound to 125 I] gastrin with a high specificity. CONCLUSION The receptors in rats meets the criteria for estblishing receptor binding assay.