Effectiveness of ischemic preconditioning on long-term myocardial preservation.
BACKGROUND
This study was designed to assess whether the protective effect of ischemic preconditioning can be adapted for myocardium undergoing 6 hr of ischemia.


METHODS
Eighteen isolated rat hearts were perfused with oxygen-bicarbonated Krebs-Henseleit buffer in the Langendorff mode for 35 min (group A, controls) or perfused in the Langendorff apparatus for 20 min, followed by 5 min of global normothermic ischemia and 10 min of buffer perfusion (group B, preconditioning) or followed by two cycles of 2.5 min of global normothermic ischemia plus 5 min of buffer perfusion (group C, preconditioning). The hearts were then arrested and preserved for 6 hr with Bretschneider's histidine-tryptophan-potassium cardioplegic solution at 4 degrees C, followed by 30 min of reperfusion. Recovery of cardiac function, postischemic enzyme leakage, and intracellular calcium concentration were compared.


RESULTS
After 6 hr of ischemia, the hearts that underwent preconditioning in groups B and C showed better recovery of left ventricular developed pressure (P<0.05), a lower end-diastolic pressure level (P<0.05), less leakage of creatine kinase, and a lower intracellular calcium concentration than those in group A. There were no statistical differences in the rate of recovery of coronary flow.


CONCLUSIONS
Our study demonstrated that ischemic preconditioning improves myocardial functional recovery after 6 hr of hypothermic preservation in the isolated rat heart. Preconditioning might be useful for preserving the heart against long-term ischemia/reperfusion injury.
Hachida
M
M
Department of Cardiovascular Surgery, The Heart Institute of Japan, Tokyo Women's Medical College, Shinjuku.
Lu
H
H
Ohkado
A
A
Hoshi
H
H
Gu
H
H
Nakanishi
T
T
Koyanagi
H
H
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002314:Cardioplegic Solutions; D003326:Coronary Circulation / Q000502:physiology*; D003402:Creatine Kinase / Q000032:analysis; D005947:Glucose; D006321:Heart / Q000502:physiology; D066298:In Vitro Techniques; D019157:Ischemic Preconditioning, Myocardial; D008353:Mannitol; D017202:Myocardial Ischemia; D015425:Myocardial Reperfusion; D009926:Organ Preservation; D011189:Potassium Chloride; D011343:Procaine; D051381:Rats; D016277:Ventricular Function, Left
C039984:Bretschneider cardioplegic solution; D002314:Cardioplegic Solutions; D008353:Mannitol; D011343:Procaine; D011189:Potassium Chloride; D003402:Creatine Kinase; D005947:Glucose; D002118:Calcium