不同剂量的降钙素基因相关肽对异丙肾上腺素致心肌损伤的保护作用

Protective effects of varied dosages of calcitonin gene related peptide(CGRP) on myocardial injuries induced by Isoprenaline

目的 研究不同剂量的降钙素基因相关肽 (CGRP)对异丙肾上腺素 (ISO)致心肌损伤的保护作用。方法 利用 ISO制造大鼠心肌缺血模型 ,观察不同剂量 CGRP对 ISO损伤心肌的影响 ,实验记录大鼠体表心电图、检测心肌酶的改变和取心肌组织行病理检查。结果 ISO致心肌缺血可导致大鼠体表心电图出现缺血改变 ,其 ST段由 0 m V下移至 - 0 .0 7± 0 .0 3m V (P <0 .0 1) ,T波低平或倒置 ,心律失常发生率 42 % ;组织病理切片发现心肌内膜下较小坏死灶甚至大范围的灶性病变。静注CGRP(3μg/kg、5μg/kg)后 ,可使 ST段恢复至 0 .0 3± 0 .0 3m V ,0 . 0 3± 0 . 0 2 m V (P均 <0 .0 1) ,T波恢复率分别为42 % ,6 7% (P均 <0 .0 1) ,心律失常消失 ;由病理切片看可减轻心肌的损伤 ,而静注 CGRP(1μg/kg)则无此作用。结 论 CGRP对缺血心肌有保护作用 ,但此作用与CGRP剂量有关 。

Objective To study the protective effects of varied dosages of CGRP on myocardial injuries brought about by Isoprenaline. Methods The rat myocardial ischemic model was established with Isoprenaline to observe the change of electrocardiogram(ECG),myocardial enzymes and pathological findings. Results There were characteristic ischemic changes of the ECG on the model,including depressed ST interval(0 VS 0.07± 0.03 mV, P <0.01),flatened or inverted T wave and 42% arrhythmic uccurrence.Microscopically examination revealed relatively small necrotic foci to comparatively large focal lesions after intravenous administration of CGRP(3μg/kg,5μg/kg).We found that the ECG changes improved significantly,including ST interval′s retur ning to 0.03±0.03mV,0.03±0.02mV( P <0.01,0.01,respectively),42% and 62% T wave′s recovery and arrhythmia′s disappearence,and that the microscopically findings revealed less myocardial injuries while 1μg/kg CGRP had no this effect. Conclusion CGRP had a protective effect on ischemic myo cardium in a dosage dependent manner,without any actions in low dosage.