Preconditioning-induced cardioprotection and release of the second messenger inositol (1,4,5)-trisphosphate are both abolished by neomycin in rabbit heart

B. Bauer, B. Z. Simkhovich, R. A. Kloner, K. Przyklenk

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

The mechanisms responsible for infarct size reduction with preconditioning remain controversial. Our aim was to determine whether release of the second messenger inositol (1,4,5)-trisphosphate (Ins(1,4,5)P3) during the preconditioning stimulus may play a role. To test this concept, Langendorff-perfused rabbit hearts underwent sham perfusion, 5 min of coronary artery occlusion (CO), or 5 min of CO + infusion of neomycin, an agent which inhibits formation of Ins(1,4,5)P3. Direct quantitation (by competitive binding assay) revealed a 2-fold increase in Ins(1,4,5)P3 content with brief ischemia vs shams (0.69 ± 0.14 vs 0.34 ± 0.05 pmol/mg tissue; p < .05) that was blocked by neomycin (0.15 ± 0.04 pmol/mg). Infarct size (by tetrazolium staining) was assessed in additional hearts that underwent 30 min of sustained CO and 2 h of reperfusion. As expected, two 5-min episodes of preconditioning ischemia reduced infarct size versus controls (30 + 6% versus 63 ± 3% of the myocardium at risk; p < .01). In contrast, infarct size was comparable (54-56% of the risk region) in neomycin-treated control and preconditioned hearts. These results demonstrate that myocardial Ins(1,4,5)P3 content is increased in response to brief preconditioning ischemia and are consistent with the concept that Ins(1,4,5)P3 may be a potential mediator of infarct size reduction with preconditioning in isolated rabbit heart.

Original languageEnglish
Pages (from-to)31-40
Number of pages10
JournalBasic Research in Cardiology
Volume94
Issue number1
DOIs
StatePublished - Feb 1999

Keywords

  • Calcium
  • Myocardial infarction
  • Myocardial ischemia
  • Second messengers
  • Signal transduction

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