Comparison of sodium pentobarbitone and urethane anaesthesia in a rat model of coronary artery occlusion and reperfusion arrhythmias: interaction with L-NAME.

The severity and incidences of arrhythmias induced by left coronary artery occlusion (7 min) and reperfusion (7 min) were compared in two groups of rats anaesthetized by using urethane (1.25 g kg-1, i.p.) or sodium pentobarbitone (60 mg kg-1, i.p.). A possible modification by nitric oxide synthesis blocker NG-nitro-L-arginine methyl ester (L-NAME; 20 mg kg-1, slow i.v. bolus) was also investigated. The ectopic activity observed in urethane-anaesthetized rats was less in number when compared to that of sodium pentobarbitone. The duration of ventricular tachycardia (VT) was significantly less in urethane group during the occlusion and reperfusion periods but incidence of ventricular fibrillation (VF) during the reperfusion was significantly higher. The administration of L-NAME caused a significant increase in the arterial blood pressure which disappeared after coronary artery occlusion in either anaesthesia groups. However, L-NAME had no significant effect on the difference observed between the two groups except the significant difference between total number of ectopic beats in both anaesthesia groups during occlusion was abolished by L-NAME treatment. These results suggest that, in this experimental model, the anaesthetic agent used can affect the severity of ischaemia-reperfusion arrhythmias and basal nitric oxide release does not have a major influence on them.