Objective To study the feasibility of additive improvement of heart protection by preconditioning with MLA and adenosine.Methods Rabbits of group A were injected with MLA, then 24?h later the hearts were isolated, mounted on a Langendorff apparatus, preconditioned with adenosine, perfused with filtered modified Krebs-Henseleit(K-H) buffer through left atria, instrumented left ventricular function monitor system and paced ventricularly at 180 beat/min. Hearts were arrested with 4?℃ modified St.Thomas solution, stored for 4?h at 4?℃ in this solution, and reperfused with K-H buffer. Left ventricular function, myocardial CK-mb leakage and tissue levels of adenosine triphosphate were measured. Groups B and C were only preconditioned with MLA or adenosine, respectively, while group D was only preserved with the modified St.Thomas solution in 4?℃.Results The left ventricular function recovery as percentage (+dp/dt max) in groups A, B, C was 70.97 ? 17.92 , 65.54 ? 22.62 , 64.36 ? 16.10 , respectively. If compared with group D ( 39.07 ? 13.78 ), the differences were significant ( P