Direct evidence of changes in myofilament responsiveness to Ca2+ during hypoxia and reoxygenation in myocardium
| Autor: | J. K. Gwathmey, Roger J. Hajjar |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
medicine.medical_specialty
Myofilament Physiology Aequorin chemistry.chemical_element In Vitro Techniques Calcium Phosphates Oxygen Consumption Myofibrils Physiology (medical) Internal medicine medicine Extracellular Animals Hypoxia biology Ryanodine Ryanodine receptor Myocardium Histological Techniques Osmolar Concentration Fissipedia Ferrets Hydrogen-Ion Concentration Hypoxia (medical) biology.organism_classification Myocardial Contraction Endocrinology chemistry biology.protein medicine.symptom Cardiology and Cardiovascular Medicine Myofibril |
| Zdroj: | American Journal of Physiology-Heart and Circulatory Physiology. 259:H784-H795 |
| ISSN: | 1522-1539 0363-6135 |
| DOI: | 10.1152/ajpheart.1990.259.3.h784 |
| Popis: | In the presence of 1 microM ryanodine, muscles loaded with the calcium indicator aequorin were stimulated at 15-20 Hz to produce steady levels of force and intracellular Ca2+ concentrations [( Ca2+]i) at various extracellular Ca2+ concentration ([Ca2+]o). After 5, 10, and 15 min of hypoxia and 3 min of reoxygenation, tetani were initiated. Force vs. [Ca2+]i relation was shifted to the right 0.11, 0.18, and 0.24 pCa units, and maximal force was down 66, 48, and 37% after start of hypoxia. During reoxygenation, the relationship was shifted up by 26%. In skinned fiber preparations, an increase in inorganic phosphate ion concentration from 0 to 10 mM and 15 mM decreased maximal force development by 32 and 53%, respectively, and shifted the pCa-force curve to the right by 0.08 and 0.14 pCa. A decrease in pH from 7.1 to 6.8 shifted the pCa-force curve to the right by 0.20 pCa units without affecting maximal force. These changes indicate that during hypoxia, a decrease in the sensitivity of the myofilaments to Ca2+ and a depression of maximal Ca2(+)-activated force occur, whereas during reoxygenation, there is an increase in maximal Ca2(+)-activated force. |
| Databáze: | OpenAIRE |
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