Effect of ATP - Sensitive Potassium Channel Opener Nicorandil on Cardioplegic Arrest in Isolated Rabbit Heart

We hypothesized that pretreatment with the adenosine triphosphate - sensitive potassium channel opener nicorandil might enhance myocardial protection and endothelial vasodilatory response to normothermic (37℃) hyperkalemic (20 mmol/L) cardioplegia during myocardialhypoxia. We studied the effect of nicorandil using supplementation of the cardioplegic solution and pretreatment with nicorandil on isovolemic left ventricular function and endothelial function by examining its influence on 5-hydroxytryptamine (5-HT) and nitroglycerin (GTN) induced vasodilatation in the isolated rabbit heart. Twenty one rabbit hearts were perfused using a modified Langendorff preparation. After baseline measurements, hearts were subjected to a 35- minute period of arrest by infusing normothermic crystalloid cardioplegic solution with and wuthout nicorandil (Group B and Group A) and thereafter maintained at 37℃. In a third group, nicorandil (10-6mol/L) was given for 3 minutes prior to the infution of cardioplegia without nicorandil (Group C).They were reperfused with Krebs - Henseleit bicarbonate buffer at 37℃ for 60 minutes. The isovolemic left ventricular function was not different in the three groups. After reperfusion, the vasodilatory effects of 5-HT and GTN were markedly attenuated in Group A. In Group B, the 5-HT response was reduced but the nitroglycerin effect was unchanged. In Group C, pretreatment of nicorandil preserves endothelial function after 35 minutes of normothermic cardioplegic arrest.

ATP - Sensiteve Potassium Channel Opener

Myocardial Protection

Vasodilatory Response