BACKGROUNDS: Ischemia and reperfusion injury decrease the release of nitricoxide by vessels endothelial cells, which influences postischaemic coronary flow and return of left ventriclehaemodynamic function. The study was conducted to answer the question how addition of L-arginine in cardioplegicand reperfusion fluids influences nitric oxide release, inducing the coronary flow and postischaemichaemodynamic heart function. MATERIALS AND METHODS: The research was conducted on 56 rats, divided randomlyinto seven groups: control (C) and six experimental groups (E), where L-arginine was administrated inincreasing doses of 0.3, 3.0 and 30.0 mM/L to cardioplegic (E1, E2 and E3 group) or reperfusion solution(E4, E5 and E6 group). To simulate a course of cardiac surgery the following stages of experiment werecarried out: initial perfusion on the nonworking and working heart, cardioplegia, cold cardioplegic arrestand reperfusion of the non-working and working heart. RESULTS: Level of nitric oxide during cardioplegicperfusion decreased in all groups. During reperfusion on non-working and working heart model we noticedthe significant increase of nitric oxide for all groups. Along with nitric oxide increase, coronary flowincreases, whereas with the decrease of level of nitric oxide, the coronary flow also diminished. Duringcardioplegic perfusion coronary flow constantly decreased in all groups and during reperfusion we observedthe new increase of coronary flow. In groups E1, E2 and E3 the increase of coronary flow was significant.CONCLUSIONS: Obtained data suggest that administration of L-arginine in the preischaemic and in the initialphase of reperfusion stimulates increase in nitric oxide release what is positively correlated with theincrease of coronary flow.

Keywords: cardioplegia, Cardiovascular Surgery, ischaemia, Nitric Oxide, Reperfusion