Enhanced tolerance of the rat myocardium to ischemia and reperfusion injury early after acute myocardial infarction.
It is now recognized that changes occurring during cardiac remodeling may influence the tolerance of the myocardium to ischemic stress. Therefore, the present study investigated the response of the post-infarcted heart to ischemia in an experimental model of ischemia and reperfusion injury and the possible underlying mechanisms. Acute myocardial infarction (AMI) was induced in Wistar male rats by ligating the left coronary artery (AMI, n = 13), while sham-operated rats were used as controls (SHAM, n = 11). At 2 weeks, cardiac dysfunction was observed in AMI, as indicated by the reduction of the left ventricular EF%. Isolated hearts were then subjected to 30 min of zero-flow global ischemia followed by 45 min of reperfusion. Ischemic contracture was significantly depressed in AMI hearts. Postischemic left ventricular end diastolic pressure (LVEDP45) in mmHg and LDH release in IU/g were markedly decreased; LVEDP45 was 52.1 (7.5) for AMI vs 96.6 (7.5),P < 0.05 and LDH release was 7.5 (1.0) in AMI vs 11.4 (0.56) in SHAM, P < 0.05. This response was associated with 2-fold increase in HSP70 expression in AMI hearts (noninfarcted segment), P < 0.05 vs SHAM and 1.7 fold increase in the expression of the phospho-HSP27, P < 0.05, while the expression of PKCepsilon was shown to be 1.4-fold less in AMI, P < 0.05. In conclusion, the post-infarcted heart seems to be resistant to ischemiareperfusion injury and heat shock protein 70 and 27 may be involved in this response.
Pantos
Constantinos
C
Dept. of Pharmacology, University of Athens, 75 Mikras Asias Ave., 11527 Goudi, Athens, Greece. cpantos@cc.uoa.gr
Mourouzis
Iordanis
I
Dimopoulos
Antonios
A
Markakis
Konstantinos
K
Panagiotou
Matthew
M
Xinaris
Christodoulos
C
Tzeis
Stylianos
S
Kokkinos
Alexandros D
AD
Cokkinos
Dennis V
DV
D000818:Animals; D003331:Coronary Vessels / Q000601:surgery; D004195:Disease Models, Animal; D055551:HSP27 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000378:metabolism; D008026:Ligation; D008297:Male; D009200:Myocardial Contraction; D009203:Myocardial Infarction / Q000378:metabolism / Q000503:physiopathology*; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000378:metabolism; D009363:Neoplasm Proteins / Q000378:metabolism; D051744:Protein Kinase C-epsilon / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013318:Stroke Volume; D013997:Time Factors; D016277:Ventricular Function, Left; D024723:Ventricular Myosins / Q000378:metabolism; D017725:Ventricular Pressure; D020257:Ventricular Remodeling
D055551:HSP27 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C486114:Hspb1 protein, rat; C000594638:MYH7 protein, rat; D009363:Neoplasm Proteins; D051744:Protein Kinase C-epsilon; D024723:Ventricular Myosins; D018995:Myosin Heavy Chains