Abstract:[Abstract] Objective To observe the effect of calcitonin gene-related peptide (CGRP) receptor antagonist CGRP8-37 on ventricular arrhythmia after acute myocardial infarction in rats. Methods Twenty-four healthy adult male Sprague-Dawley rats weighing 250-300 g were selected and randomly assigned into three groups (n = 8): control group (sham group), coronary artery occlusion group (CAO group) and CGRP8-37 intervention for coronary artery occlusion in advance group (CGRP8-37-CAO group). The times of ventricular arrhythmia from 10 min before CAO to 60 min after CAO were calculated and analyzed statistically according to the types of ventricular arrhythmia including one ventricular premature beat, two consecutive ventricular premature beats, three consecutive ventricular premature beats, more than three consecutive ventricular premature beats. Results CAO could induce the occurrence of ventricular arrhythmias, the occurrence time was concentrated on 0-12 min of early ischemia and peaked around 6 min after CAO. Pretreatment of CGRP8-37 before CAO could significantly increase the frequency of arrhythmias, and the time course was significantly extended from 0-12 min in CAO group to 0-20 min in CGRP8-37-CAO group. Peaked time of ventricular premature beats appeared in 12 min after CAO. The occurrence of ventricular arrhythmias in sham group, CAO group and CGRP8-37-CAO group had no significant differences 10 min before CAO (P > 0.05). Compared with sham group, the occurrence of ventricular arrhythmias was increased in CAO group and CGRP8-37-CAO group, the differences were highly statistically significant (P < 0.01). Compared with CAO group, the occurrence of ventricular arrhythmia in CGRP8-37-CAO group was increased, the difference was highly statistically significant (P < 0.01). The time of differences appeared in ventricular arrhythmia was concentrated on 20, 30, 40 min after CAO. Conclusion CGRP8-37 can significantly increase the occurrence of ventricular arrhythmia after acute myocardial infarction in rats.