STUDIES ON IDENTIFICATION OF ENDOGENOUS DIGITALISLIKE FACTOR,AND THE ROLE IN WATER-ELECTROLYTES BALANCE AND BLOOD PRESSURE REGULATION

我们用实验动物研究中枢神经系统在内源性洋地黄样因子(S)产生中的作用已有15年以上。最近，我们发现大鼠肾上腺髓质也含有洋地黄样免疫反应。因此，我们认为肾上腺髓质来源的细胞系可以产生(EDLF)。事实上，我们发现来源于嗜铬细胞瘤细胞的PC-12细胞产生哇巴因样免疫反应物质，并通过重复层析对其进行了表征。此外，在这个培养体系中，EDLF的产量明显但略有增加(由于这一证据尚未发表，我们不想在这里说明材料)。在本研究期间，我们收集了大量的经生长因子刺激后的培养液。经过几种洗脱柱后，对EDLF进行了纯化，并对含有哇巴因免疫活性的组份进行了液-质联用分析。结果，该物质被鉴定为哇巴因。这肯定是哺乳动物可以内源性产生洋地黄的第一个证据，因为其他报告一直都有这样一种可能性，即被识别的物质来自饮食来源。然而，也有其他一些材料表现出不同的层析特性。分析现在正在进行中。此外，我们还鉴定了血浆中的哇巴因结合蛋白，它是一段免疫球蛋白。

We have been studying the role of central nervous system in the production of endogenous digitalislike factor (s) (EDLF) by using experimental animals for more than 15 years. Recently, we found that the adrenal medulla also contained digitalislike immunoreactivity in rats. Therefore, we thought that the cell-line of adrenomedullary origin could produce (EDLF). In fact, we found that PC-12 cells which is originated from pheochrocytoma cells produced ouabainlike immunoreactive substance, which was characterized by repeated chromatography. Furthermore, production of EDLF in this culture system was obviously but slightly augmented by a growth factor (since this evidence has not been published, we do not want to indicate the material here). In the present study period, we collected a great amount of culture medium after stimulating with the growth factor. After passing serveral kinds of elution columns, the EDLF was purified, and the fraction which contains ouabainlike immunoreactivity was analyzed by liquid chromatography with mass spectrometry. As the result, the substance was identified to be ouabain. This must be the first evidence that mammals can endogenously produce digitalis, because the other reports always have had the possibility that the identified material is of the diet origin. However, some other materials which showed the different chromatographic characteristics were there. The analysis is now going on. Furthermore, we identified the ouabain-binding protein in plasma, which was a fragment of IgG.