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Regulatory proteins in hamster cardiomyopathy
1Department of Medicine, Montefiore Medical Center/Albert Einstein College of Medicine, Bronx, New York.
Circulation Research
|May 1, 1990
Summary
Myopathic hamsters exhibit impaired cardiac function due to altered calcium regulation in cardiac muscle proteins. This study reveals decreased inhibitory action of regulatory proteins on actomyosin ATPase activity, contributing to heart dysfunction.
Area of Science:
- Cardiovascular Biology
- Muscle Physiology
- Biochemistry
Background:
- Genetic myopathic hamsters show altered cardiac myofibrillar ATPase regulation and myosin isozyme shifts.
- Previous studies indicated abnormalities in multiple contractile apparatus components.
Purpose of the Study:
- To investigate abnormalities in regulatory proteins (troponin and tropomyosin) of the actomyosin system in myopathic hamsters.
- To enzymatically study myosin, actin, troponin, and tropomyosin from normal and myopathic hamster muscles.
Main Methods:
- Proteins were isolated from skeletal and cardiac muscle of control and cardiomyopathic hamsters.
- Sodium dodecyl sulfate gel electrophoresis was used to analyze protein differences.
- Actomyosin ATPase activity was measured to assess calcium sensitivity.
Main Results:
- Differences were observed in troponin I and troponin C regions of myopathic skeletal muscle.
- Cardiac muscle samples showed similarities in troponin mobility between control and myopathic hamsters.
- Calcium sensitivity was significantly decreased in actomyosin reconstituted with myopathic troponin-tropomyosin.
Conclusions:
- Regulatory proteins in myopathic hamster skeletal and cardiac muscle show decreased inhibitory action on Mg2(+)-actomyosin ATPase activity.
- Loss of calcium regulation, along with myosin heavy chain shifts, may contribute to impaired cardiac function in myopathic hamsters.