Tepperman B L, Soper B D, Emery S K
Prostaglandins. 1984 Oct;28(4):477-84. doi: 10.1016/0090-6980(84)90236-3.
It has been reported that prostacyclin (PGI2) is the predominant species of prostanoid in rat oxyntic mucosa. However since PGI2 is inactivated under physiological conditions it has not been possible to demonstrate specific PGI2 binding to the rat stomach. Therefore a stable PGI2 analogue, Iloprost, was chosen as ligand in this study. Binding of labelled Iloprost to the 20,000 xg homogenate fraction of rat oxyntic mucosa was specific, dissociable, saturable and dependent upon the temperature and time of incubation. Neither tritiated PGE2 nor 6 keto PGF1 alpha displayed any significant specific binding to rat stomach. A Scatchard plot of the equilibrium binding data for Iloprost was curvilinear and could be resolved into at least two binding sites. The average parameters determined from Scatchard analysis were: dissociation constants of 1.8 X 10(-11) M and 7.1 X 10(-8) M and corresponding binding site concentrations of 12.0 pmole/mg and 4800 pmoles/mg protein respectively. PGI2 was less potent than unlabelled Iloprost in displacing 3H-Iloprost from its binding site. The addition of PGE2 to the incubation medium resulted in an increase in 3H-Iloprost binding. It is concluded that rat oxyntic mucosa has specific binding sites for PGI2-like agents but not for either PGE2 or 6 keto PGF1 alpha.
据报道，前列环素（PGI2）是大鼠胃黏膜中前列腺素的主要种类。然而，由于PGI2在生理条件下会失活，因此无法证明其与大鼠胃有特异性结合。所以，本研究选用了一种稳定的PGI2类似物伊洛前列素作为配体。标记的伊洛前列素与大鼠胃黏膜20,000 xg匀浆部分的结合具有特异性、可解离性、饱和性，且依赖于孵育温度和时间。氚标记的PGE2和6-酮-PGF1α均未显示出与大鼠胃有任何显著的特异性结合。伊洛前列素平衡结合数据的Scatchard图呈曲线，可分解为至少两个结合位点。通过Scatchard分析确定的平均参数为：解离常数分别为1.8×10^(-11) M和7.1×10^(-8) M，相应的结合位点浓度分别为12.0 pmol/mg和4800 pmol/mg蛋白质。PGI2从其结合位点取代3H-伊洛前列素的能力比未标记的伊洛前列素弱。向孵育培养基中添加PGE2会导致3H-伊洛前列素结合增加。结论是，大鼠胃黏膜有PGI2类似物的特异性结合位点，但对PGE2或6-酮-PGF1α均无特异性结合位点。
