Reduction of infarct size with D-myo-inositol trisphosphate: role of PI3-kinase and mitochondrial K(ATP) channels
Department of Emergency Medicine; Department of Anesthesiology
1-Phosphatidylinositol 3-Kinase; Alkaloids; Animals; Benzamides; Benzophenanthridines; Cardiotonic Agents; Chromones; Decanoic Acids; Enzyme Inhibitors; Hydroxy Acids; Inositol 1,4,5-Trisphosphate; Ischemic Preconditioning, Myocardial; Mitochondria, Heart; Morpholines; Myocardial Infarction; Myocardium; Phenanthridines; Potassium Channels; Protein Kinase C-epsilon; Rabbits; Stereoisomerism
Life Sciences | Medicine and Health Sciences
Prophylactic treatment with D-myo-inositol 1,4,5-trisphosphate hexasodium [D-myo-Ins(1,4,5)P3], the sodium salt of the endogenous second messenger Ins(1,4,5)P3, triggers a reduction of infarct size comparable in magnitude to that seen with ischemic preconditioning (PC). However, the mechanisms underlying D-myo-Ins(1,4,5)P3-induced protection are unknown. Accordingly, our aim was to investigate the role of four archetypal mediators implicated in PC and other cardioprotective strategies (i.e., PKC, PI3-kinase/Akt, and mitochondrial and/or sarcolemmal K(ATP) channels) in the infarct-sparing effect of D-myo-Ins(1,4,5)P3. Fifteen groups of isolated buffer-perfused rabbit hearts [5 treated with D-myo-Ins(1,4,5)P3, 5 treated with PC, and 5 control cohorts] underwent 30 min of coronary artery occlusion and 2 h of reflow. One set of control, D-myo-Ins(1,4,5)P3, and PC groups received no additional treatment, whereas the remaining sets were infused with chelerythrine, LY-294002, 5-hydroxydecanoate (5-HD), or HMR-1098 [inhibitors of PKC, PI3-kinase, and mitochondrial and sarcolemmal ATP-sensitive K+ (K(ATP)) channels, respectively]. Infarct size (delineated by tetrazolium staining) was, as expected, significantly reduced in both D-myo-Ins(1,4,5)P3- and PC-treated hearts versus controls. D-myo-Ins(1,4,5)P3-induced cardioprotection was blocked by 5-HD but not HMR-1098, thereby implicating the involvement of mitochondrial, but not sarcolemmal, K(ATP) channels. Moreover, the benefits of D-myo-Ins(1,4,5)P3 were abrogated by LY-294002, whereas, in contrast, chelerythrine had no effect. These latter pharmacological data were corroborated by immunoblotting: D-myo-Ins(1,4,5)P3 evoked a significant increase in expression of phospho-Akt but had no effect on the activation/translocation of the cardioprotective epsilon-isoform of PKC. Thus PI3-kinase/Akt signaling and mitochondrial K(ATP) channels participate in the reduction of infarct size afforded by prophylactic administration of D-myo-Ins(1,4,5)P3.
DOI of Published Version
Am J Physiol Heart Circ Physiol. 2006 Feb;290(2):H830-6. Epub 2005 Sep 23. Link to article on publisher's site
American journal of physiology. Heart and circulatory physiology
Przyklenk, Karin; Maynard, Michelle; and Whittaker, Peter, "Reduction of infarct size with D-myo-inositol trisphosphate: role of PI3-kinase and mitochondrial K(ATP) channels" (2005). Open Access Articles. 122.