THE EFFECT OF CALCITONIN-GENE-RELATED PEPTIDE ON ISCHEMIC REPERFUSION-INDUCED ARRHYTHMIAS IN RATS

Thirty-six wistar rats (150-250 g body weight) were randomly divided i nto two groups. There were equal numbers of male and female rats in ea ch group. Each group of rats was given either 0.5 mi normal saline or calcitonin gene-related peptide (CGRP, 20 mu g/kg dissolved in 0.5 ml normal saline) intravenously within 5 min. Coronary arteries of these rats were occluded 5 min after administration. The coronary artery was then released from ligation 5 min later. The heart beat of all rats w as monitored for 30 min. An electrocardiogram was recorded using limb leads and below-xiphoid leads. There was no ischemic reperfusion-induc ed arrhythmia in the first minute of reperfusion in CGRP group, while 13 rats occurred ischemic reperfusion-induced arrhythmia (ventricular tachycardia and fibrillation) in the normal saline group (P < 0.05). A verage onset time of ischemic reperfusion-induced arrhythmia was 377.5 +/- 141.0 s/sim. In the CGRP group, compared with 42.7 +/- 55.4 s/sim . for the normal saline group (P < 0.01). The duration of ischemic rep erfusion-induced arrhythmia was 15.0 +/- 30.6 s/sim. In the CGRP group compared with 104.4 +/- 143.8 s/sim. in the normal group (P < 0.05), There was no death in the CGRP group, but six rats in the normal salin e group died (P < 0.05). The results showed that CGRP could reduce and delay the occurrence of ischemic reperfusion-induced arrhythmia such as ventricular tachycardia and fibrillation, especially in the early p eriod, and decrease the mortality. The mechanism is not clear and need s to be studied further.