Differences in prolonged ischemia length using ischemic preconditioning in the rabbit heart. Tolerable limitation time for surgically induced myocardial ischemia during normothermic cardiac operation.
BACKGROUND
To determine the effect of the tolerable limitation time of prolonged ischemia after ischemic preconditioning on postischemic functional recovery and infarct size reduction in the rabbit heart.


METHODS
White rabbits (n=30) were used for Langendorff perfusion. Control hearts were perfused at 37 degrees C for 180 min; 30 min global ischemia hearts (30GI) received 30 min global ischemia and 120 min reperfusion; IPC+30GI hearts received 5 min zero flow global ischemia and 5 min reperfusion prior to 30 min global ischemia; 20 min global ischemia hearts (20GI) received 20 min global ischemia and 120 min reperfusion; IPC+20GI hearts received 5 min zero flow global ischemia and 5 min reperfusion prior to 20 min global ischemia.


RESULTS
Infarct size in the 30GI hearts was 33.5+/-4.0% and 1.7+/-0.5% in the control hearts. The 20GI hearts and IPC+30GI hearts decreased infarct size, as compared with the 30GI hearts (13.0+/-1.8% and 16.6+/-1.7%, respectively; p<0.001, 20GI vs 30GI; p<0.01, IPC+30GI vs 30GI; p>0.05, 20GI vs IPC+30GI) but did not enhance postischemic functional recovery. The IPC+20GI hearts (3.5+/-0.6%) significantly decreased infarct size as compared with the 20GI hearts (p<0.05, IPC+20GI vs 20GI), and there was no significant difference between the IPC+20GI and the control hearts (p>0.05), but the IPC+20GI hearts did not enhance postischemic functional recovery.


CONCLUSIONS
A 20 min ischemia may be the tolerable limitation time of prolonged ischemia after ischemic preconditioning in an isolated rabbit heart model.
Uematsu
M
M
Department of Surgery, Division II, Kobe University of Medicine, Kobe, Japan.
Okada
M
M
D000818:Animals; D003326:Coronary Circulation / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology; D019157:Ischemic Preconditioning, Myocardial / Q000379:methods*; D009203:Myocardial Infarction / Q000473:pathology / Q000503:physiopathology*; D015428:Myocardial Reperfusion Injury / Q000473:pathology / Q000503:physiopathology*; D009206:Myocardium / Q000473:pathology; D009924:Organ Culture Techniques; D011817:Rabbits; D013997:Time Factors; D016277:Ventricular Function, Left / Q000502:physiology