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A physiologically relevant hyperthermia selectively activates constitutive hsp70 in H9c2 cardiac myoblasts and confers oxidative protection.

Authors: Su, CY  Chong, KY  Chen, J  Ryter, S  Khardori, R  Lai, CC 
Citation: Su CY, etal., J Mol Cell Cardiol. 1999 Apr;31(4):845-55.
Pubmed: (View Article at PubMed) PMID:10329212
DOI: Full-text: DOI:10.1006/jmcc.1998.0923

Whole body hyperthermia (42-43 degrees C for 15-20 min) elicits the formation of heat shock proteins (hsps) and improves cardiac recovery from subsequent ischemia/reperfusion. However, the beneficial effects of this response are compromised by initial tissue injury, which limits its clinical applicability. Using a simplified myocardial model (rat heart-derived H9c2 myoblasts) a hypothesis was tested that chronic, mild hyperthermia is as effective as acute heat shock in inducing the heat shock response. Our results indicate that 39 degrees C pre-conditioning evoked thermotolerance and oxidative resistance, but caused no detectable adverse effects. An improved survival after hydrogen peroxide (H2O2) exposure (40-54 microm for 3 h) was first observed in cells pre-conditioned at 39 degrees C for 24 h. As the duration of thermal pre-incubation increased, cells became more resistant than the control (37 degrees C) to a greater toxicity of H2O2(68 microm). An optimal oxidative protection developed by;4 days at 39 degrees C and this persisted for as long as the cells were incubated at this temperature. Three hsps are known to modulate cellular antioxidant defenses: the constitutive-hsp70 (hsc70), its inducible counterpart (hsp70), and hsp27. The authors found that mild hyperthermia selectively induced only hsc70, which demonstrates a lower temperature threshold for activation of hsc70. The initial protection against the milder H2O2challenge correlated with a homogenous distribution of pre-existing hsc70. The subsequent optimal protection was associated with an identical distribution pattern and a moderate increase of hsc70. These observations suggest that mild hyperthermia induces a beneficial adaptive response, in which hsc70 plays a critical role.

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RGD ID: 10059424
Created: 2015-08-18
Species: All species
Last Modified: 2015-08-18
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