Beneficial effect of the addition of nitroglycerin to the cardioplegic solution on the cold-stored reperfused isolated rat heart.

We discuss here the effect of the addition of trinitroglycerin to the cardioplegic solution on the isolated rat heart after eight hours of storage. This effect was evaluated by measuring cardiac function as well as myocardial calcium and enzymes. Male Wistar rats were divided into three groups based on the concentration of trinitroglycerine in the cardioplegic solution. In the control group, the fluid used was a crystalloid cardioplegic solution (K+ 25 mEq/L) without trinitroglycerin and for groups I and II, trinitroglycerin was added at concentrations of 2 micrograms/ml and 5 micrograms/ml, respectively. All hearts were arrested with the cardioplegic solution at 4 degrees C and then immersed for eight hours in Euro-Collins' solution at 4 degrees C. The postperfusion coronary flow showed higher rates for groups I and II than for the control group (p < 0.05), while the difference between groups I and II was not significant. In group I, the total concentrations of creatine kinase-MB, lactate and malondialdehyde after reperfusion showed the lowest levels; this group also had the lowest content of myocardial calcium. These results indicate that the addition of nitroglycerin, especially at a concentration of 2 micrograms/ml, to the cardioplegic solution elicits better cardiac function for immersed rat heart.