Protective effects of
cysteine (Cys),
N-acetylcysteine (NAC),
cysteamine (MEA),
cystamine (CSSC) and aminopropylmethylisothiourea (
APMT) on
ischemia/reperfusion induced arrhythmias were studied in isolated Langendorff perfused rat hearts. The arrhythmias were caused by
ligation of the anterior descending branch of the left coronary artery for 10 min and reperfused for 5 min. The drugs were dissolved in saline (NS) and perfused through a peristaltic pump system at 0.1, 0.6 or 3.6 mumol/min (n = 10), starting from 10 min before
ligation up to 5 min after reperfusion. The control hearts were perfused with NS. The results showed that Cys, NAC and MEA pursued at 0.6-3.6 mumol/min significantly reduced the incidence of
ventricular fibrillation (VF), which were 80-90% in control and 0-20% in 3 treated groups, with P less than 0.01-0.001. The duration of
ventricular tachycardia (VT) + VF was 3.0 +/- 1.6 min in control and were 0.2 +/- 0.2, 0.2 +/- 0.1 and 1.2 +/- 2.1 min in Cys, NAC and MEA groups, respectively (with P less than 0.01-0.001). Coronary flow (CF) were remarkably reduced to about 50% during
ligation in NS, but remained at normal levels in three treated groups. There were no significant protective effects on arrhythmias in CSSC and
APMT perfused hearts. CF of CSSC and
APMT groups were even less than those of control. The structure-activity analysis suggested that the SH group may play a crucial role in the protective effect of SH compounds on
ischemia/reperfusion induced arrhythmias. The mechanism of protection was briefly discussed in this paper.