Effects of calcium overload on relaxation in cultured heart cells
| Autor: | Dennis S. Miura, Stefan Biedert, William H. Barry |
|---|---|
| Rok vydání: | 1981 |
| Předmět: |
medicine.medical_specialty
Time Factors Contraction (grammar) Muscle Relaxation Sodium chemistry.chemical_element Chick Embryo Calcium Ouabain Choline Veratrine Cell wall chemistry.chemical_compound Internal medicine medicine Animals Molecular Biology Cells Cultured Myocardium Endoplasmic reticulum Time constant Heart Myocardial Contraction Endocrinology chemistry Biophysics Cardiology and Cardiovascular Medicine Muscle Contraction medicine.drug Choline chloride |
| Zdroj: | Journal of Molecular and Cellular Cardiology. 13:949-961 |
| ISSN: | 0022-2828 |
| DOI: | 10.1016/0022-2828(81)90471-5 |
| Popis: | Effects of alterations in transsarcolemmal sodium and calcium gradients on relaxation and calcium content were studied in spontaneously contracting tissue cultured monolayers of chick embryo ventricular cells. Cell wall motion during relaxation could be resolved into two kinetic phases. The first phase was rapid, with a time constant, τ 1 , of 30 to 40 ms and presumably reflects Ca uptake by sarcoplasmic reticulum. The second phase had a longer time constant, τ 2 , which varied under different experimental conditions from 50 to 200 ms. Cell wall motion during this second phase of relaxation continued until the next contraction occurred. At high external Ca, τ 1 and τ 2 were prolonged, coincident with a marked increase in Ca content as determined by 45 Ca labelling. Reduction of the transsarcolemmal Na gradient by external substitution of NaCl with choline chloride, by increasing internal [Na] by exposure of the cells to 5 μg/ml veratrine, or by exposure to ouabain (10 −5 m ), also prolonged τ 1 and τ 2 and increased cellular Ca content. These findings suggest that Ca overload in cultured heart cells can occur as a consequence of altered NaCa exchange, and can result in marked but reversible impairment of relaxation. |
| Databáze: | OpenAIRE |
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