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Adaptive mechanisms that preserve cardiac function in mice without myoglobin
A P Meeson1, N Radford, J M Shelton
1Departments of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Circulation Research
|April 17, 2001
Summary
Mice lacking myoglobin often die in utero due to cardiac failure. However, surviving mice develop adaptations to compensate for the lack of myoglobin, ensuring normal heart function.
Area of Science:
- Cardiovascular Physiology
- Developmental Biology
- Molecular Adaptation
Background:
- Myoglobin is an oxygen-binding protein found in cardiac and skeletal muscle.
- Previous studies suggested myoglobin-deficient mice survive to adulthood without apparent deficits.
Purpose of the Study:
- To investigate the role of myoglobin during embryonic development.
- To identify compensatory mechanisms in myoglobin-deficient mice.
Main Methods:
- Generation of myoglobin-deficient mouse models.
- Embryonic and fetal survival analysis.
- Assessment of cardiac function and molecular adaptations (gene expression, vascularity).
Main Results:
- Myoglobin-deficient embryos exhibit high mortality at midgestation due to cardiac failure.
- Surviving fetuses (post-gestational day 12.5) show no increased mortality.
- Adaptations include increased vascularity and induction of hypoxia-inducible factors, stress proteins, and vascular endothelial growth factor.
- These adaptations maintain myocardial oxygen consumption under stress.
Conclusions:
- Myoglobin is essential for normal cardiac function during embryonic development.
- Adaptive responses can fully compensate for the absence of myoglobin in surviving individuals.
- This highlights the plasticity of physiological systems in response to genetic defects.