Cytochrome c mRNA levels decrease in senescent rat heart
R B Biggs1, R M Hanley, P R Morrison
1Department of Physiology and Cell Biology, University of Texas Medical School, Houston 77225.
Abstract:
The concentration of mitochondria decreases in the heart as rodents age from maturity to senescence. The reason for this change is not known. One purpose of the present study was to determine if cytochrome c mRNA, representative of proteins of the inner mitochondrial membrane, decreased in the hearts of Fischer 344 rats as they aged from 12 to 24 months. Twenty-two percent less cytochrome c mRNA existed per given quantity of extracted RNA from the heart in 24-month-old rats as compared with the 12-month-old group. No change in the quantities of cardiac alpha-actin mRNA, Ca2+/calmodulin protein kinase II mRNA or 18S rRNA was noted between 12- and 24-month-old hearts. Thus, the decrease in cytochrome c mRNA suggests that decreases in mRNAs for proteins of the inner mitochondrial membrane could play some role in the diminished concentration of mitochondria that exists in the senescent heart.
Insights
Mitochondrial concentration declines in aging rodent hearts. This study found decreased cytochrome c mRNA in older rats, suggesting a role for inner mitochondrial membrane protein mRNA decline in reduced mitochondrial content during aging.
Area of Science:
- Gerontology
- Molecular Biology
- Cardiovascular Science
Background:
- Mitochondrial concentration in the heart diminishes with age in rodents.
- The underlying causes for age-related mitochondrial decline remain largely unknown.
Purpose of the Study:
- To investigate whether cytochrome c mRNA levels decrease in aging Fischer 344 rat hearts.
- To determine if this decrease correlates with the known reduction in mitochondrial concentration during senescence.
Main Methods:
- Quantitative analysis of cytochrome c mRNA in Fischer 344 rat hearts at 12 and 24 months of age.
- Comparison of cytochrome c mRNA levels with control mRNAs (alpha-actin, Ca2+/calmodulin protein kinase II, 18S rRNA) to assess specificity.
Main Results:
- A 22% reduction in cytochrome c mRNA was observed in 24-month-old rats compared to 12-month-old rats.
- No significant changes were detected in cardiac alpha-actin mRNA, Ca2+/calmodulin protein kinase II mRNA, or 18S rRNA between the age groups.
Conclusions:
- The observed decrease in cytochrome c mRNA suggests a potential role for reduced expression of inner mitochondrial membrane proteins in age-related mitochondrial loss.
- This finding contributes to understanding the molecular mechanisms underlying cardiac aging and mitochondrial dysfunction.
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