[Equivalent cardioprotective effect of "half-conditioning" and post-conditioning in a canine model of myocardial ischemia and reperfusion].
OBJECTIVE
To study the effects of "half-conditioning", a modified postconditioning process, on myocardial injury induced by severe myocardial ischemia/reperfusion (I/R) in anesthetized dogs.


METHODS
Mongrel dogs of both sexes were subjected to 40 min ischemia (coronary blood flow reduced by 80% via controlled coronary stenosis). At the end of ischemia, dogs were randomly received one of the following treatments: (1) control, reperfusion for 3 h (n = 7); (2) post-conditioning, three cycles of ischemia 30 s followed by reperfusion for 30 s and then reperfusion for 3 h (n = 7); (3) half-conditioning, coronary blood flow recovered to 50% for 2 min, then 80% for 2 min, thereafter 100% for 3 h (n = 7). Electrocardiogram (ECG), arterial blood pressure and left ventricular pressure were monitored throughout the experiment. Plasma creatine kinase (CK) and lactate dehydrogenase (LDH) activity were measured spectrophotometrically. Myocardial necrosis was defined by TTC-staining.


RESULTS
Compared with control animals, arrhythmia incidence, LVEDP at 2 and 3 h reperfusion, CK and LDH were significantly reduced in animals received post-conditioning and half-conditioning treatments, infarct size as a percentage (%) of the area at risk was also significantly reduced by post-conditioning and half-conditioning treatments. No differences were observed in the post-conditioning and half-conditioning groups.


CONCLUSIONS
Half-conditioning exerts the same cardioprotective effects on post-ischemic hearts as postconditioning.
Fan
Qian
Q
Beijing Chaoyang Hospital Affiliated of Capital University of Medical Sciences, Beijing 100020, China.
Yang
Xin-chun
XC
Wang
Shu-yan
SY
Chen
Jin
J
Chi
Hong-jie
HJ
Liu
Sheng-hui
SH
D000818:Animals; D004195:Disease Models, Animal; D004285:Dogs; D005260:Female; D019157:Ischemic Preconditioning, Myocardial; D008297:Male; D015428:Myocardial Reperfusion Injury / Q000628:therapy*