Abstract
Activation of sphingosine kinase/sphingosine 1-phosphate-mediated signaling has emerged as a critical cardioprotective pathway in response to acute ischemia/reperfusion injury. Application of exogenous sphingosine 1-phosphate (S1P) in cultured cardiac myocytes subjected to hypoxia or treatment of isolated hearts either before ischemia or at the onset of reperfusion (pharmacologic preconditioning or postconditioning) exerts prosurvival effects. Synthetic congeners of S1P mimic these responses. Gene-targeted mice null for the sphingosine kinase 1 isoform whose hearts are subjected to ischemia/reperfusion injury exhibit increased infarct size and respond poorly either to ischemic preconditioning or to ischemic postconditioning. Measurements of cardiac sphingosine kinase activity and S1P parallel these observations. High-density lipoprotein is a major carrier of S1P, and studies of hearts in which selected S1P receptors have been deleted implicate the S1P cargo of high-density lipoprotein in cardioprotection. These observations have considerable relevance for future therapeutic approaches to acute and chronic myocardial injury.