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Diabetes-induced decrease in the mRNA coding for sarcoplasmic reticulum Ca(2+)-ATPase in adult rat cardiomyocytes
1Laboratory of Molecular Cardiology, Diabetes Research Institute, Düsseldorf, Federal Republic of Germany.
Abstract:
The present study examined the level of the mRNA coding for the sarcoplasmic reticulum (SR) Ca(2+)-ATPase in isolated ventricular myocytes from streptozotocin-diabetic rats and genetically obese (fa/fa) rats using Northern blotting techniques. In both animal models one single transcript with a mean size of 4.12 kb could be detected. In insulin-deficient rats the Ca(2+)-ATPase transcript level decreased by 51% when compared to normal rats. In obese animals a modest decrease in the Ca(2+)-ATPase mRNA content to 77% of lean controls has been detected. Decreased mRNA expression of the SR Ca(2+)-ATPase may partly explain the delayed diastolic relaxation observed in the diabetic heart.
Insights
Diabetic and obese rat hearts show reduced sarcoplasmic reticulum Ca(2+)-ATPase mRNA levels. This decrease in calcium pump gene expression may contribute to impaired heart relaxation in diabetes.
Area of Science:
- Cardiovascular Physiology
- Molecular Biology
- Endocrinology
Background:
- Diabetes and obesity are associated with cardiac dysfunction.
- Sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) is crucial for cardiac muscle relaxation.
- Alterations in SERCA gene expression may underlie diabetic cardiomyopathy.
Purpose of the Study:
- To investigate the mRNA levels of sarcoplasmic reticulum Ca(2+)-ATPase in two distinct models of cardiac disease: streptozotocin-induced diabetes and genetic obesity.
- To correlate changes in Ca(2+)-ATPase mRNA with potential functional deficits in the diabetic heart.
Main Methods:
- Isolation of ventricular myocytes from streptozotocin-diabetic rats and genetically obese (fa/fa) rats.
- Quantification of sarcoplasmic reticulum Ca(2+)-ATPase mRNA using Northern blotting techniques.
- Comparison of mRNA levels between diseased and control animal groups.
Main Results:
- A single transcript for sarcoplasmic reticulum Ca(2+)-ATPase (4.12 kb) was detected in all groups.
- Insulin-deficient (diabetic) rats exhibited a significant 51% decrease in Ca(2+)-ATPase mRNA levels compared to normal rats.
- Genetically obese rats showed a modest 23% reduction in Ca(2+)-ATPase mRNA content relative to lean controls.
Conclusions:
- Reduced mRNA expression of the sarcoplasmic reticulum Ca(2+)-ATPase is evident in both diabetic and obese rat hearts.
- These molecular changes may partially explain the observed delayed diastolic relaxation in the diabetic heart.
- Further research is warranted to explore the therapeutic potential of targeting SERCA expression in metabolic cardiomyopathies.