Under these conditions, hearts of S1P3-KO mice exhibited worse postischemic contractile recovery (82 ± 3% vs. 52 ± 3% decrease in LVDevP compared to preischemic baseline value in S1P3-KO and WT mice, respectively) and larger infarct size (11 ± 3% vs. 1 ± 3% in S1P3-KO and WT mice, respectively) than WT hearts, indicating that ischemia-induced myocardium-related S1P actions are cardioprotective via activation of S1P3. Here, MBTPS1 is linked to ischemia.