Effects of polyamines on apoptosis induced by simulated ischemia/reperfusion injury in cultured neonatal rat cardiomyocytes

We incubated neonatal Sprague-Dawley rat cardiornyocytes in primary culture in a medium simulating ischermia (consisting of hypoxia plus serum deprivation) for 2 It, then re-incubated them for 24 It in normal culture medium to establish a model of simulated ischemia/reperfusion (I/R) injury. Apoptotic cell death was measured by MTT assay, TUNEL staining and flow cytometry. Morphological alterations were assessed by transmission electron microscopy, the expression of caspases-3 and -9 and Bcl-2 and the release of cytochrome c by Western blotting, and the intracellular free-calcium concentration ([Ca2+](i)) by laser confocal scanning microscopy. The results showed that pretreatment with 10 mu mol/l spermine or spermidine significantly inhibited apoptosis in the I/R cells, suppressed the expression of caspases-3 and -9 and cytochrome c release, up-regulated Bcl-2 expression and decreased [Ca2+](i). However, pretreatment with 10 mu mol/l putrescine had the opposite effects. Evidence for this double-edged effect of polyamines on apoptosis in I/R-injured cardiomyocytes is presented for the first time. It may suggest a novel pharmacological target for preventing and treating cardiac ischemia/reperfusion injury. (c) 2007 International Federation for Cell Biology. Published by Elsevier Ltd. All rights reserved.