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Progressive exercise preconditioning protects against circulatory shock during experimental heatstroke
Ching-Hsia Hung1, Nen-Chung Chang, Bor-Chih Cheng
1Department of Physical Therapy, National Cheng Kung University, Tainan, Taiwan 701.
Shock (Augusta, Ga.)
|April 19, 2005
Summary
Progressive exercise training for three weeks significantly protects against heatstroke by increasing heat shock protein (HSP) 72. This preconditioning enhances cardiovascular function and reduces inflammatory markers during heatstroke.
Area of Science:
- Physiology
- Molecular Biology
- Exercise Science
Background:
- Heat shock protein (HSP) 72 is known to protect against hypotension during heatstroke.
- Endurance exercise can induce HSP72 expression in various organs, including the heart.
Purpose of the Study:
- To investigate if progressive exercise preconditioning confers cardiovascular protection during heatstroke by inducing HSP72 overexpression.
- To assess the impact of exercise duration on HSP72 induction and heatstroke protection.
Main Methods:
- Rats were subjected to progressive exercise training for 1, 2, or 3 weeks.
- Heatstroke was induced by exposure to high ambient temperature (43°C).
- Cardiovascular parameters, blood gases, TNF-alpha levels, and HSP72 expression were measured.
Main Results:
- Three weeks of exercise training significantly protected against hyperthermia, hypotension, and reduced cardiac output during heatstroke.
- This protection correlated with HSP72 overexpression in the heart, liver, and adrenal glands.
- The beneficial effects were lost when HSP72 levels returned to baseline 10 days after training cessation.
Conclusions:
- Progressive exercise preconditioning, specifically for three weeks, confers significant protection against heatstroke-induced cardiovascular dysfunction and hyperthermia.
- HSP72 overexpression induced by exercise is a key mechanism for this protection.
- The protective effects are transient and dependent on sustained HSP72 levels.