Distribution of sphingosine 1-phosphate, a bioactive sphingolipid, in rat tissues.

Although a growing number of reports on the bioactivities of sphingosine 1-phosphate (Sph-1-P) in various systems have been appearing recently, current evidence for the involvement of Sph-1-P in signal transduction or cellular function(s) consists largely of data on cellular and biochemical effects of exogenous Sph-1-P. In this study, we measured Sph-1-P contents in various rat tissues. When the amount of this sphingoid base was measured by its N-acetylation into [3H]C2-ceramide 1-phosphate with [3H]acetic anhydride, we could detect Sph-1-P in all rat tissues examined. We also got unexpected findings that Sph-1-P exists most abundantly in testis = intestine > spleen (in the order of Sph-1-P abundance when its amounts were adjusted to the phospholipid levels). Our new data on Sph-1-P distribution in rat tissues may imply novel bioactivities for Sph-1-P.