| Co-Investigator(Kenkyū-buntansha) |
SATOH Kaneo Faculty of Medicine, Yamanashi Medical University, Research Assistant, 医学部, 教務職員 (20242662)
OZAKI Yukio Faculty of Medicine, Yamanashi Medical University, Professor, 医学部, 教授 (30134539)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1997: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1996: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
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.
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