Pyruvate improves myocardial tolerance to reperfusion injury by acting as an antioxidant: A chemiluminescence study

Abstract

<h2>Abstract</h2> <b>Background:</b> There is indirect evidence that pyruvate improves myocardial tolerance to ischemia by scavenging oxygen radicals during reperfusion. The objectives of this study were to evaluate (1) lucigenin-enhanced chemiluminescence (LEC) as a method to measure oxygen radical (OR) production in vitro and in vivo and (2) the antioxidant effect of pyruvate during myocardial reperfusion. <b>Methods:</b> LEC was measured in vitro by adding to lucigenin (1) increasing concentrations of H₂O₂, (2) H₂O₂ and different concentrations of catalase, and (3) H₂O₂ plus pyruvate. Isolated rat hearts perfused with Krebs Henseleit-Lucigenin inside a chemiluminescence chamber were subjected to equilibration, ischemia, and reperfusion without (control) or with pyruvate. Developed pressure, contractility, compliance, and chemiluminescence were recorded. <b>Results:</b> In vitro, LEC directly correlated with H₂O₂ concentrations (r²= 0.997) and decreased in the presence of catalase or pyruvate. During myocardial reperfusion there was a surge of chemiluminescence that peaked at 4 minutes. Pyruvate decreased the initial reperfusion peak (9.8 ± 0.3 × 10³ cpm in pyruvate group vs 12.4 ± 0.9 × 10³ cpm in control; <i>p</i> < 0.05) and the total amount of chemiluminescence generated during reperfusion (65.7 ± 12 × 10³ in pyruvate group vs 117.1 ± 8.2 × 10³ counts in control; <i>p</i> < 0.05). Pyruvate improved recovery of function after ischemia reperfusion. <b>Conclusions:</b> LEC is a sensitive indicator of H₂O₂ concentrations and can evaluate the effect of antioxidants in vitro. It is a continuous, sensitive, and direct measurement of OR production in vivo. LEC is ideal for the evaluation of antioxidant interventions and provides direct evidence that pyruvate acts as an antioxidant while improving myocardial function during reperfusion. (Surgery 1998;124:92-9.)