15-F2t-ISOPROSTANE and 5-F2t-ISOPROSTANE ARE NOT TRIGGERS OF MYOCARDIAL PRECONDITIONING.

1. Myocardial ischaemia–reperfusion in humans is associated with increased formation of 15-F2t-isoprostane and 5-F2t-isoprostane (15-F2t-IsoP and 5-F2t-IsoP, respectively). Whether this formation is relevant clinically remains controversial. The present study was performed in order to evaluate the ability of the isoprostanes 15-F2t-IsoP and 5-F2t-IsoP to reduce myocardial ischaemic injury in rat isolated heart.2. Rats were divided into six groups. Hearts were excised, perfused retrogradely and pretreated with vehicle (ethanol 5.10⁻⁷ and 2.10⁻⁹ mol/L;n = 6), subjected to ischaemic preconditioning (n = 8) or pretreated with the isoprostanes 15-F2t-IsoP (3.10⁻¹⁰ and 3.10⁻⁷ mol/L;n = 8) or 5-F2t-IsoP (10⁻⁹ mol/L;n = 8). After a 5 min treatment−5 min washout period, hearts were submitted to 30 min global ischaemia, followed by a 120 min reperfusion period.3. The infarct-to-ventricle zone ratio was significantly reduced in ischaemic preconditioned (20.6 ± 2.6%) compared with vehicle groups (44.5 ± 4.3 and 51.3 ± 2.5% in groups pretreated with 5.10⁻⁷ or 2.10⁻⁹ mol/L ethanol, respectively). Pretreatment with either isoprostane had no cardioprotective effect; the infarct-to-ventricle ratios were 43.1 ± 2.2, 49.4 ± 5.9 and 44.5 ± 5.0% for groups treated with 3.10⁻¹⁰ mol/L 15-F2t-IsoP, 3.10⁻⁷ mol/L 15-F2t-IsoP or 10⁻⁹ mol/L 5-F2t-IsoP, respectively.4. These data provide evidence that the isoprostanes 15-F2t-IsoP and 5-F2t-IsoP are not implicated in early myocardial preconditioning at concentrations similar to those found in the human coronary sinus following coronary angioplasty. [ABSTRACT FROM AUTHOR]

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