ADENOSINE, ADDED TO ST-THOMAS-HOSPITAL CARDIOPLEGIC SOLUTION, IMPROVES FUNCTIONAL RECOVERY AND REDUCES IRREVERSIBLE MYOCARDIAL DAMAGE

St Thomas' Hospital cardioplegic solution is commonly used to arrest h earts during surgery. Pursuing the hypothesis that the cardioprotectiv e properties of adenosine could be a beneficial adjunct to a solution containing high K+ and Mg2+, we tested a low and a high adenosine conc entration added to this cardioplegic solution, aiming at improved reco very of function and energy status. We arrested 18 working rat hearts by a 3-minute infusion with the solution without or with 50 mu M or 5 mM adenosine. We induced 30 minute stop-flow ischemia at 37 degrees C, followed by 10 minute washout (Langendorff mode) and 20 minute reperf usion (working heart). Control cardioplegia induced electrical arrest in 19.8+/-5.5 s. This took 9.1+/-0.9 and 12.7+/-1.8 s in the presence of 50 mu M and 5 mM adenosine, respectively (p<0.05 vs no adenosine) . During reperfusion a regular electrocardiogram appeared after 1.9+/- 0.3 minutes in controls, after 1.0+/-0.0 and 1.7+/-0.2 minutes in hea rts treated with low and high-dose adenosine, respectively (p<0.05 vs no adenosine). After 20 minute reperfusion, the pressure-rate product had recovered to 65+/-17% in controls, and to 107+/-11* and 72+/-11% of preischemic values in hearts treated with 50 mu M and 5 mM adenosi ne, respectively (*p<0.05 vs other groups). There was a good correlat ion between reperfusion function recovery and the postischemic release of creatine kinase, an index for irreversible cellular damage. This a ssociation was absent with ATP content, which increased with the adeno sine concentration. Our data indicate a cellular protection by adenosi ne with the low but not with the high-dose, unrelated to high-energy p hosphate levels. Conclusion: Fifty mu M adenosine, added to St. Thomas ' Hospital cardioplegic solution, accelerated cardioplegic arrest, red uced creatine kinase release, and improved reperfusion function in iso lated working rat hearts.