Contraction and resting stiffness of isolated cardiac muscle: effects of inotropic agents
| Autor: | W. Shapiro, K. Taubert, G. H. Templeton, James T. Willerson |
|---|---|
| Rok vydání: | 1977 |
| Předmět: |
Male
Inotrope Digoxin medicine.medical_specialty Contraction (grammar) Physiology chemistry.chemical_element Calcium Ouabain Contractility Norepinephrine Physiology (medical) Internal medicine medicine Animals Hypoxia Papillary muscle Chemistry Cardiac muscle Papillary Muscles Hypoxia (medical) equipment and supplies Myocardial Contraction Elasticity Stimulation Chemical Oxygen Endocrinology medicine.anatomical_structure Cats Female Stress Mechanical medicine.symptom Cardiology and Cardiovascular Medicine medicine.drug |
| Zdroj: | American Journal of Physiology-Heart and Circulatory Physiology. 232:H275-H282 |
| ISSN: | 1522-1539 0363-6135 |
| Popis: | The purpose of this study was to test the hypothesis that either hypoxia and its combined effects with extracellular calcium (Ca), digoxin, and ouabain, or these positive inotropic agents acting alone or in combination, influence contraction and resting stiffness of isolated papillary muscle. Stiffness was measured utilizing the sinusoidal forcing function technique. Neither an increase in extracellular calcium concentration (from 2.5 to 4.0 mM) nor digoxin or ouabain in either Ca concentration altered contraction or resting stiffness in the well-oxygenated environment. Resting stiffness for any given resting tension was increased at the end of hypoxia only in the presence of digoxin, and this occurred in both 2.5 mM Ca (P less than 0.02) and in 4.0 mM Ca (P = 0.05). Contraction stiffness for any given tension was increased in 2.5 mM Ca by hypoxia alone (P less than 0.05) and by hypoxia in the presence of digoxin (P less than 0.005) and ouabain (P less than 0.02), but was not increased in any experiments conducted in 4.0 mM Ca. The conclusions from these data are that certain experimental conditions of the study evoked different directional changes in stiffness and contractility. Further, changes in contraction stiffness are not always paralleled by changes in resting stiffness. |
| Databáze: | OpenAIRE |
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