Measurement of plasma sphingosine 1-phosphate

尽管鞘氨醇1-磷酸（Sph-1-P）据报道参与多种细胞过程，并且这种生物活性鞘脂的生理作用已被强烈提出，但很少有研究表明在生理条件下人体样本（包括体液和细胞）中存在Sph-1-P。在这项研究中，我们确定了Sph-1-P是人类血浆和血清的正常成分。血浆和血清Sph-1-P水平为191 （[SY.+-]）。[) 79和484 [](]SY.+-。[) 82pmol /ml（平均值）[][) SD,n=8)。此外，当对6名健康成人的配对血浆和血清样本进行Sph-1-P测量时，发现血清Sph-1-P/血浆Sph-1-P比值为2.65 （]SY.+-）。[) 1.26（平均值）[](SD)。在凝血过程中释放的Sph-1-P最有可能是来自血小板，因为血小板比其他血细胞更丰富地储存Sph-1-P，并在刺激时将其储存的部分Sph-1-P释放到细胞外。我们还研究了血浆中sph -1- p的相关代谢。[<@D13@>D1H] Sph在血浆中稳定且完全不被代谢，但在富血小板血浆中被迅速并入血小板并主要代谢为Sph-1- p。[<@D13@>D1H]发现血浆中Sph不变，表明血浆中不含降解Sph-1- p所需的酶。总之，血小板可以将Sph转化为Sph-1- p，并且是后者在血液中的储存场所。鉴于Sph-1-P的多种生物学作用，活化血小板释放Sph-1-P可能参与多种生理和病理生理过程，包括血栓形成、止血、动脉粥样硬化和伤口愈合。

Although sphingosine 1-phosphate (Sph-1-P) is reportedly involved in diverse cellular processes and the physiological roles of this bioactive sphingolipid have been strongly suggested, few studies have revealed the presence of Sph-1-P in human samples, including body fluids and cells, under physiological conditions. In this study, we identified Sph-1-P as a normal constituent of human plasma and serum. The Sph-1-P levels in plasma and serum were 191 (]SY.+-。[) 79 and 484 (]SY.+-。[) 82 pmol/ml (mean (]SY.+-。[) SD,n=8), respectively. Furthermore, when Sph-1-P was measured in paired plasma and serum samples obtained from 6 healthy adults, the serum Sph-1-P/plasma Sph-1-P ratio was found to be 2.65 (]SY.+-。[) 1.26 (mean (]SY.+-。[) SD). It is most likely that the source of discharged Sph-1-P during blood clotting is platelets, because platelets abundantly store Sph-1-P compared with other blood cells, and release part of their stored Sph-1-P extracellularly upon stimulation. We also studied Sph-1-P-related metabolism in plasma. [<@D13@>D1H] Sph was stable and not metabolized at all in plasma, but was rapidly incorporated into platelets and metabolized mainly to Sph-1-P in platelet-rich plasma. [<@D13@>D1H] Sph was found to be unchanged in plasma, revealing that plasma does not contain the enzymes needed for Sph-1-P degradation. In summary platelets can convert Sph into Sph-1-P,and are storage sites for the latter in the blood. In view of the diverse biological effects of Sph-1-P,the release of Sph-1-P from activated platelets may be involved in a variety of physiological and pathophysiological processes, including thrombosis, hemostasis, atherosclerosis and wound healing.