title: Combined sphingosine, S1P and ischemic postconditioning rescue the heart after protracted ischemia.
abstract: Both sphingosine and sphingosine-1-phosphate (S1P) were able to protect the ex vivo rat heart from ischemia reperfusion injury when added to the perfusion medium at the time of reperfusion after a 40min ischemia (postconditioning). Inhibitor studies revealed distinct mechanisms of protection, with S1P employing a G-protein coupled receptor pathway and sphingosine a cyclic nucleotide dependent protein kinase pathway. However, both restored ischemia-induced depletion of phospho-AKT. Extending the ischemia to 75min reduced protection by both S1P and sphingosine, but protection could be enhanced by employing them in combination. Extending the time of ischemia further to 90min almost eliminated cardioprotection by S1P or sphingosine; and their combination gave only modest protection. However, when S1P plus sphingosine was combined with a novel ramped ischemic postconditioning regimen, left ventricle developed pressure recovered by 66% and there was only a 6% infarct size. The data indicate that detrimental changes are accumulating during protracted ischemia but for up to 90min this damage is not irreversible and hearts can still recover with proper treatment.
authors.affiliation: Liver Study Unit (151-K), Department of Veterans Affairs Medical Center, 4150 Clement Street, San Francisco, CA 94121, USA.
authors.forename: Donald A
authors.initials: DA
authors.lastname: Vessey
authors.forename: Luyi
authors.initials: L
authors.lastname: Li
authors.forename: Michael
authors.initials: M
authors.lastname: Kelley
authors.forename: Joel S
authors.initials: JS
authors.lastname: Karliner
mesh_terms: D000818:Animals; D002316:Cardiotonic Agents / Q000494:pharmacology*; D003331:Coronary Vessels / Q000187:drug effects / Q000503:physiopathology; D006352:Heart Ventricles / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology*; D066298:In Vitro Techniques; D008246:Lysophospholipids / Q000494:pharmacology*; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D015427:Reperfusion Injury / Q000378:metabolism / Q000503:physiopathology*; D015398:Signal Transduction / Q000187:drug effects; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology*
chemical_list: D002316:Cardiotonic Agents; D008246:Lysophospholipids; D043562:Receptors, G-Protein-Coupled; C060506:sphingosine 1-phosphate; D051057:Proto-Oncogene Proteins c-akt; D013110:Sphingosine