Myocardial protective effect of ischemic preconditioning and its mechanism in immature rabbit heart
- VernacularTitle:缺血预处理对幼兔心肌保护作用及其机制探讨
- Author:
Bin ZHU
;
Su MIN
;
Cun LONG
- Publication Type:Journal Article
- Keywords:
Ischemic preconditioning, myocardial;
Myocardial reperfusion injury;
Potassium channel: Animals, newborn
- From:
Chinese Journal of Anesthesiology
1994;0(06):-
- CountryChina
- Language:Chinese
-
Abstract:
Objective To investigate whether ischemic preconditioning( IPC) could protect against ischemia-reperfusion injury in immature rabbit heart and the role of KATP channel in the mechanism of myocardial protection. Methods New Zealand rabbits aged 14-21 days weighing 220-280g were used. The animals were anesthetized and heparinized. Chest was opened and heart was quickly removed and aorta was connected to Langendorff preparation within 30 s. The hearts were perfused with Krebs-Henseleit buffer balanced with gas mixture(O2: CO2 = 95% : 5% ) at 60cmH2O2(perfusion pressure) . IPC consisted of 5 mm global ischimia plus 10 mm reperfusion. Glibenclamide was used as KATP channel blocker. Cardiac arrest was induced with cold(4℃ ) St Thomas Ⅱ cardioplegic solution and heart was made globally ischemic by withholding perfusion for 45 mm followed by 40 mm reperfusion. Thirty immature rabbit hearts were randomly divided into four groups: group Ⅰ( n= 9 control) was subjected to ischemia-reperfusion only; groupⅡ(n= 9 IPC + ischemia-reperfusion); group Ⅲ(n = 6 glibenclamide + ischemia-reperfusion) and group Ⅳ( n= 6 glibenclamide + IPC + ischemia-reperfusion) . Coronary flow(CF), HR, left ventricle developed pressure( LVDP) and ? dP/dt max were monitored before ischemia/IPC/glibenclamide( baseline value) and 5, 10, 20 and 40 mm after reperfusion and were expressed as percentage of their baseline values. Arrhythmia scores were recorded. Coronary effluent was collected at 10 miii after reperfusion was started for determination of CK-MB level. At the end of reperfusion 200mg myocardium was taken from apex for determination of ATP content. Results The group Ⅱ(IPC group) showed best results. The recovery of CF, HR, LVDP and ?dp/dt max, was best among the four groups. The incidence of arrhythmia was low and less CK-MB leaked out. Myocardial ATP content was better preserved. Pretreatment with glibenclamide completely abolished the myocardial protection provided by IPC but did not affect ischemiareperfusion injury. Conclusions IPC can protect against ischemia-reperfusion injury in immature rabbit bean. Activation of KATh channel is involved in the mechanism of myocardial protection of IPC.
