[Effects of chloride ion channel and its blockers on myocardial ischemia reperfusion arrhythmias in rabbits].

OBJECTIVE

To explore the impact of chloride ion channel and its blockers 4, 4'-diisothiocyanostilbene-2, 2'-disulfonic acid (DIDS), cyanato-stilbene-2, 2'-disulfonic acid (SITS) and 5-nitro-2-(3-phenyl-propylamino) benzoic acid (NPPB) on arrhythmias caused by myocardial ischemia reperfusion.

METHODS

A total of 40 rabbits were divided into control, ischemia reperfusion, DIDS low-dose, DIDS high-dose, SITS low-dose, SITS high-dose, NPPB low-dose and NPPB high-dose groups. Myocardial ischemia reperfusion model was established by ligation of anterior descending coronary artery. And standard limb lead II of electrocardiogram (ECG) was continuously monitored during the experimental process. Then comparisons of heart rate, ECG P wave, R wave, T wave, ST segment changes and arrhythmias score were made between the above groups.

RESULTS

During 30-minute ischemia, compared with the control group, all other groups showed significantly decreased heart rate ((199.8 ± 4.0) - (253.6 ± 2.1) vs (267.0 ± 3.4), all P < 0.01), elevated ECG P wave ((0.216 ± 0.019) - (0.356 ± 0.024) vs (0.186 ± 0.019), all P < 0.01), R wave ((0.564 ± 0.017) - (1.138 ± 0.048) vs (0.506 ± 0.018), all P < 0.01), T wave ((0.542 ± 0.013) - (0.856 ± 0.045) vs (0.278 ± 0.015), all P < 0.01) and ST segment ((0.326 ± 0.027) - (0.668 ± 0.054) vs (0.024 ± 0.023), all P < 0.01) and increased arrhythmia score ((1.4 ± 0.5) - (4.6 ± 0.5) vs (0.4 ± 0.5), all P < 0.01). Compared with the ischemia reperfusion group, the above indices significantly improved in the intervention groups (heart rate: (214.8 ± 3.4) - (246.8 ± 4.0) vs (199.8 ± 4.0), all P < 0.01; P wave: (0.216 ± 0.019) - (0.316 ± 0.011) vs (0.356 ± 0.024), all P < 0.01; R wave: (0.564 ± 0.017) - (0.980 ± 0.035) vs (1.138 ± 0.048), all P < 0.01; T wave: (0.542 ± 0.013) - (0.792 ± 0.026) vs (0.856 ± 0.045), all P < 0.01; ST segment: (0.326 ± 0.027) - (0.596 ± 0.018) vs (0.668 ± 0.054), all P < 0.01; arrhythmia score: (1.4 ± 0.5) - (3.8 ± 0.4) vs (4.6 ± 0.5), all P < 0.01). Among which, the DIDS group was the best, followed by the SITS group and then the NPPB group. And the high-dose subgroups were better than those of the low-dose subgroups. During 60-minute reperfusion, the decreased heart rate upswing significantly in each group and the elevated P wave, R wave, T wave and ST segment fell back gradually. The DIDS group showed the most obvious amplitude change, followed by the SITS group and then the NPPB group. And the high-dose subgroups were better than those of the low-dose subgroups. The arrhythmia score during reperfusion showed the same trend.

CONCLUSION

Chloride ion channel is involved in the generation of myocardial ischemia reperfusion arrhythmia.Early application of chloride ion channel blockers DIDS, SITS and NPPB may improve the ECG manifestations and reduce the degree of reperfusion arrhythmia.