The aim of this work was to assess effects of a novel asanquineous
cardioplegic solution (CP-5), buffered with
trisamine (pH 7.6+/-0.1 at 22 degrees C) and containing 21.5 mM
aspartic acid and 20.0 mM
mannitol, on postischemic functional and metabolic recovery of isolated rat heart. A modified
Ringer solution with 25 mM KCl (pH 7.6+/-0.1 at 22 degrees C) and the St. Thomas'
cardioplegic solution (pH 7.8+/-0.1 at 22 degrees C) were used as controls. Osmolarity of all
cardioplegic solutions were 340+/-5. After 20-min initial perfusion according to Neely (steady state) the hearts were subjected to 40-min normothermal total
ischemia followed by 30-min antegrade reperfusion.
Cardioplegic solutions were infused prior to
ischemia at rate of the initial coronary flow for 5 min at room temperature. During reperfusion the hearts of CP-5 group completely recovered coronary flow and significantly enhanced restoration of the majority functional indices compared to the hearts in both control groups. This effect was combined with less
lactate accumulation and preservation of higher
ATP and
phosphocreatine (PCr) levels in the heart tissue by the end of
ischemia and, probably was induced by inclusion of
aspartic acid into composition of CP-5. By the end of reperfusion the hearts treated with CP-5 completely recovered PCr content and restored
ATP level up to 65.2+/-4.6% of initial one. A better energy state of reperfused hearts in CP-5 group was accompanied by reduction of myocardial
lactate tissue to the preischemic value. Restoration of
ATP, PCr and
lactate content was significantly poor in both control groups during reperfusion. The least formation of a spin adduct of the short life
oxygen radicals was found in the myocardial effluent of the hearts of CP-5 group at the early reperfusion using EPR technique. These data suggest a reduced release of
oxygen radical generating systems from postischemic myocardium into perfusate due to
antioxidant effect of
mannitol. The obtained results substantiate addition of
aspartic acid and
mannitol to the asanquineous
cardioplegic solution, buffered with
trisamine, to enhance efficacy of myocardial protection against
ischemia and
reperfusion injury.