Structural analysis of endogenous digitalis and studies on the role of it in electrolytes and blood pressure control. In particular, studies on a novel substance, marinobufagenin with double hydrogen.

对钠-钾-三磷酸腺苷酶(Na，K-ATPase)的抑制作用比哇巴因强。通过高效液相(LC)、质谱联用(LC/MS)、核磁共振(NMR)等多步骤分析，发现这些二烯内酯类化合物在人体血液中循环存在。TCB比MBG多两个氢气，TCB的血浆浓度几乎是MBG的两倍，两者之间的相关性极显著。因此，我们认为TCB被水解为MBG。由于TCB的浓度远高于MBG，因此认为TCB是主要的内源性洋地黄。这是第一个表明哺乳动物样本中存在TCB的报告。此外，比较了正常人和终末期肾功能衰竭患者的血药浓度，发现患者血浆中的血药浓度几乎是正常人的两倍。因此，TCB和MBG都可能作为电解质的生理调节剂，从而调节血压。然后，我们制备了TCB的单抗，但不幸的是，它也与MBG发生交叉反应，并建立了酶联免疫吸附试验(ELISA)。由于该体系对血浆成分有干扰，仅适用于尿样的检测。用该酶联免疫吸附试验检测了大鼠的钠负荷效应，发现高盐饮食大鼠的TCB/MBG排泄量高于正常饮食大鼠。

Inhibition of sodium-potassium adenosine triphosphatase (Na,K-ATPase) by marinobufagenin (MBG) or telocinobufagin (TCB) are more potent than that of ouabain. We found that those bufadienolides are circulating in human blood, upon analyzing the structure by using multiple steps of liquid chromatography (LC) and mass-spectrometry (LC/MS), nuclear magnetic resonance (NMR). TCB has two more hydrogen than MBG.Plasma concentration of TCB was almost double of MBG, the correlation among them was highly significant. Therefore, we thought that the TCB is hydrolysed to MBG.Since the concentration of TCB is much higher than MBG, TCB was thought to be the cardinal endogenous digitalis. This is the first report to show the existence of TCB in mammalian samples. Furthermore, the concentration was compared in normal subjects and patients with terminal renal failure, and it was almost twice higher in the patient plasma as compared to it in normal subjects. Therefore, both TCB and MBG may be functioning as the physiological regulator of electrolytes and consequently blood pressure.Then, we made monoclonal antibody for TCB, but unfortunately it cross-reacted with MBG too, and enzyme-linked immunosorbent assay (ELISA) was developed. Because this ELISA system was interfered with constituents of plasma, it was useful only for measurement of urine samples. By using this ELISA, effects of sodium-loading was tested in rats, we found that rats with high salt diet excreted more TCB/MBG than in rats with normal diet.