Cardioprotective effects of N-acetylcysteine: the reduction in the extent of infarction and occurrence of reperfusion arrhythmias in the dog.

We have studied the cardioprotective effect of N-acetylcysteine in the dog. In mongrel dogs of either sex, the left anterior descending coronary artery was ligated for a period of 2 hours behind the origin of its first diagonal branch. After this period, dogs in a treated group were administered 100 mg of N-acetylcysteine/kg body weight while a control group remained untreated. This was followed by a 2-hour period of reperfusion. The extent of necrosis was determined using the triphenyltetrazolium method. Presence or absence of collaterals was established at the same time. The incidence of ventricular arrhythmias was monitored throughout the study. Compared with 11 dogs of the control group, 10 dogs treated with N-acetylcysteine showed a decrease of 32.7% in the extent of infarction. The extent of infarction, expressed as the percentage of the left ventricular myocardium at risk, was 55.0 +/- 7.0% in the control group and 37.0 +/- 12.6% in the treated group (P less than 0.01). N-acetylcysteine also statistically significantly decreased the incidence of ventricular arrhythmias over the period of reperfusion. Compared with the control group, the difference was evident as early as the first 5-10 minutes of reperfusion, becoming most pronounced at the 60th minute (P less than 0.001). We conclude that N-acetylcysteine is effective in limiting the extent of infarction and significantly reduces the incidence of reperfusion ventricular arrhythmias.