Sphingosine‐1‐Phosphate Receptor 1 Regulates Cardiac Function by Modulating Ca2+ Sensitivity and Na+/H+ Exchange and Mediates Protection by Ischemic Preconditioning oleh Petra Keul, Marcel M. G. J. van Borren, Alexander Ghanem, Frank Ulrich Müller, Antonius Baartscheer, Arie O. Verkerk, Frank Stümpel, Jan Sebastian Schulte, Nazha Hamdani, Wolfgang A. Linke, Pieter van Loenen, Marek Matus, Wilhelm Schmitz, Jörg Stypmann, Klaus Tiemann, Jan‐Hindrik Ravesloot, Astrid E. Alewijnse, Sven Hermann, Léon J. A. Spijkers, Karl‐Heinz Hiller, Deron Herr, Gerd Heusch, Michael Schäfers, Stephan L. M. Peters, Jerold Chun, Bodo Levkau