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Calcium antagonist receptors in cardiomyopathic hamster: selective increases in heart, muscle, brain
Insights
Syrian cardiomyopathic hamsters exhibit hereditary myocardial necrosis, a condition linked to calcium overload. This cardiac disease, treatable with verapamil, shows increased calcium antagonist receptors and brain synaptosome uptake, suggesting a role in pathogenesis.
Area of Science:
- Cardiology
- Molecular Biology
- Genetics
Background:
- Syrian cardiomyopathic hamsters possess a hereditary condition characterized by progressive myocardial necrosis.
- This condition shares similarities with human cardiac hypertrophy and is associated with cellular calcium overload.
- The calcium antagonist verapamil has demonstrated preventative effects on the observed lesions.
Purpose of the Study:
- To investigate the role of calcium channels and calcium antagonist receptors in the pathogenesis of cardiomyopathy in Syrian hamsters.
- To explore the relationship between calcium overload and the observed myocardial necrosis.
Main Methods:
- Quantification of calcium antagonist receptor binding sites in various tissues (heart, brain, skeletal muscle, smooth muscle) of cardiomyopathic hamsters compared to controls.
- Measurement of calcium-45 uptake into brain synaptosomes in cardiomyopathic hamsters.
Main Results:
- Markedly increased numbers of calcium antagonist receptor binding sites were observed in the heart, brain, skeletal muscle, and smooth muscle of cardiomyopathic hamsters.
- Enhanced uptake of calcium-45 into brain synaptosomes was noted in these hamsters.
- These findings suggest alterations in calcium regulation and receptor expression.
Conclusions:
- The increased prevalence of calcium antagonist receptors and associated voltage-sensitive calcium channels may play a significant role in the development of this cardiomyopathy.
- Understanding these mechanisms could offer insights into human cardiac hypertrophy and related calcium channelopathies.
Abstract:
The Syrian cardiomyopathic hamster has a hereditary disease in which a progressive myocardial necrosis mimics human forms of cardiac hypertrophy. Lesions are associated with calcium overload and can be prevented with the calcium antagonist verapamil. Numbers of receptor binding sites for calcium antagonists in heart, brain, skeletal muscle, and smooth muscle were markedly increased in cardiomyopathic hamsters. The uptake of calcium-45 into brain synaptosomes was also increased in cardiomyopathic hamsters. The increase in calcium antagonist receptors and related voltage-sensitive calcium channels may be involved in the pathogenesis of this cardiomyopathy.