Short-term exercise training can improve myocardial tolerance to I/R without elevation in heat shock proteins.
We examined the effects of 3 days of exercise in a cold environment on the expression of left ventricular (LV) heat shock proteins (HSPs) and contractile performance during in vivo ischemia-reperfusion (I/R). Sprague-Dawley rats were divided into the following three groups (n = 12/group): 1) control, 2) exercise (60 min/day) at 4 degrees C (E-Cold), and 3) exercise (60 min/day) at 25 degrees C (E-Warm). Left anterior descending coronary occlusion was maintained for 20 min, followed by 30 min of reperfusion. Compared with the control group, both the E-Cold and E-Warm groups maintained higher (P < 0.05) LV developed pressure, first derivative of pressure development over time (+dP/dt), and pressure relaxation over time (-dP/dt) throughout I/R. Relative levels of HSP90, HSP72, and HSP40 were higher (P < 0.05) in E-Warm animals compared with both control and E-Cold. HSP10, HSP60, and HSP73 did not differ between groups. Exercise increased manganese superoxide dismutase (MnSOD) activity in both E-Warm and E-Cold hearts (P < 0.05). Protection against I/R-induced lipid peroxidation in the LV paralleled the increase in MnSOD activity whereas lower levels of lipid peroxidation were observed in both E-Warm and E-Cold groups compared with control. We conclude that exercise-induced myocardial protection against a moderate duration I/R insult is not dependent on increases in myocardial HSPs. We postulate that exercise-associated cardioprotection may depend, in part, on increases in myocardial antioxidant defenses.
Hamilton
K L
KL
Baylor College of Medicine, Cardiology Research, Veterans Affairs Medical Center, Houston, Texas 77030, USA.
Powers
S K
SK
Sugiura
T
T
Kim
S
S
Lennon
S
S
Tumer
N
N
Mehta
J L
JL
D000818:Animals; D004789:Enzyme Activation; D005260:Female; D016166:Free Radical Scavengers / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000378:metabolism*; D019157:Ischemic Preconditioning, Myocardial / Q000379:methods; D015227:Lipid Peroxidation; D009043:Motor Activity; D017202:Myocardial Ischemia / Q000503:physiopathology*; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000378:metabolism*; D010805:Physical Conditioning, Animal; D051381:Rats; D017207:Rats, Sprague-Dawley; D013482:Superoxide Dismutase / Q000378:metabolism; D013696:Temperature; D013997:Time Factors; D016277:Ventricular Function, Left
D016166:Free Radical Scavengers; D006360:Heat-Shock Proteins; D013482:Superoxide Dismutase