Analysis of sphingosine 1-phosphate receptors involved in constriction of isolated cerebral arteries with receptor null mice and pharmacological tools

Background and purpose: Sphingosine 1-phosphate (S1P) selectively and potently constricts isolated cerebral arteries, but this response has not been pharmacologically characterized. Experimental approach: The receptor subtype(s) involved in S1P-induced cerebrovascular constriction were characterized using genetic (S1P ₂ and S1P ₃ receptor null mice) and pharmacological tools (phospho-FTY720, a S1P _1/3/4/5 receptor agonist; SEW2871, a S1P ₁ receptor agonist, JTE-013, a S1P ₂ receptor antagonist, VPC23019, a S1P _1/3 receptor antagonist). Isolated basilar or peripheral (femoral, mesenteric resistance) arteries, from either rat or mouse, were studied in a wire myograph. Key results: S1P concentration-dependently constricted basilar artery in rat, wild-type (WT) and S1P ₂ null mice, but barely affected vascular tone in S1P ₃ null mice. Vasoconstriction to U46619 (a thromboxane analogue) or to endothelin-1 did not differ between WT, S1P ₂ and S1P ₃ null mice. JTE-013 inhibited not only S1P-induced vasoconstriction, but also KCl-, U46619- and endothelin-1-induced constriction. This effect was observed in WT as well as in S1P ₂ null mice. VPC23019 increased the concentration-dependent vasoconstriction to S1P in both rat and mouse basilar arteries with intact endothelium, but not in rat basilar artery without endothelium. Phospho-FTY720 concentration-dependently constricted rat basilar arteries, but not femoral or mesenteric resistance arteries, while SEW2871 did not induce any response in the same arteries. Conclusions and implications: S1P constricts cerebral arteries through S1P ₃ receptors. The purported S1P ₂ receptor antagonist JTE-013 does not appear to be selective, at least in rodents. Enhancement of S1P-induced contraction by VPC23019 might be related to blockade of S1P ₁ receptors and NO generation.