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Diminished heat shock response in the aged myocardium
1School of Physical and Health Education, University of Toronto, Ontario, Canada. Locke@PHE.utoronto.ca
Cell Stress & Chaperones
|December 1, 1996
Summary
Aging impairs the heart's ability to produce protective heat shock proteins (Hsps). Aged hearts showed reduced Hsp response and failed to gain protection from heat stress, unlike younger hearts.
Area of Science:
- Cardiovascular Science
- Molecular Biology
- Gerontology
Background:
- Heat shock proteins (Hsps), particularly Hsp72, are linked to myocardial protection.
- Aging is associated with a diminished heat shock response.
Purpose of the Study:
- To investigate if aged hearts exhibit an altered heat shock response and reduced myocardial protection compared to adult hearts.
- To assess the impact of aging on heat shock factor 1 (Hsf1) activation and Hsp72 expression following heat stress.
Main Methods:
- Adult and aged Fischer 344 rats were subjected to heat stress (41°C for 10 min).
- Hearts were analyzed for Hsf1 activation, Hsp72 mRNA and protein levels, and Hsf1 protein content post-heat stress.
- Myocardial protection was evaluated using the Langendorff isolated heart model to assess recovery from ischemia.
Main Results:
- Aged hearts showed a 47% reduction in Hsf1 activation and decreased Hsp72 mRNA and protein levels compared to adult hearts.
- Myocardial Hsf1 protein content was comparable between aged and adult animals.
- Adult hearts pre-conditioned by heat stress demonstrated enhanced postischemic recovery, while aged hearts did not.
Conclusions:
- Aged hearts have an impaired capacity to induce protective heat shock proteins following stress.
- This reduced Hsp response in aged hearts may contribute to their increased susceptibility to stress-induced injury.