Beneficial effect of adenosine during reperfusion following prolonged cardioplegic arrest

The aim of the study was to investigate the effect of reperfusion with adenosine after prolonged cardioplegic arrest in the isolated working rat heart.

After 3 h or hypothermic (20 degrees C) ischaemic arrest with multidose (every 30 min) infusions of St Thomas's Hospital cardioplegic solution No 1, rat hearts were reperfused with either ordinary perfusion fluid (Krebs-Henseleit bicarbonate buffer) or with additional adenosine (1 mg x litre-1) for 15 min prior to assessing recovery of function.

Hearts (n = 10) in each group) were obtained from male rats weighing 250-300 g.

Mean coronary flow during the period of reperfusion was increased from 11.8(SEM 0.8) ml x min-1 with ordinary perfusate to 17(0.7) ml x min-1 with adenosine reperfusate (p less than 0.001). Mean recoveries of functional indices (as percent of preischaemic control values) in hearts receiving ordinary reperfusates v adenosine reperfusates were: peak aortic pressure 76.2(2.8)% upsilon 86.9(2.2)%, dP/dt 35.6(6.0)% upsilon 66.2(4.3)%, aortic flow 26.1(7.4)% upsilon 60.9(4.2)%, coronary flow 50.1(3.4% upsilon 75.6(3.6)%, and cardiac output 31.4(6.4)% upsilon 64.5(3.2)%. Recovery of all indices was significantly superior with adenosine than without (peak aortic pressure p less than 0.01, other indices p less than 0.001). A parallel series of experiments showed that the nucleotide content of both groups was similar at the end of the 15 min reperfusion period.

Improvement in functional recovery occurs with low dose adenosine during reperfusion. This is likely to be due to an increase in coronary flow to the microvasculature rather than to an increase in intramyocardial ATP.