Effect of temperature and calcium on force-frequency relationships in mammalian ventricular myocardium
| ISSN: |
1432-2013
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| Keywords: |
Force-Frequency Relationship ; Temperature ; Human Myocardium ; Extracellular Calcium
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| Source: |
Springer Online Journal Archives 1860-2000
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| Topics: |
Medicine
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| Notes: |
Summary The effects of temperature and calcium on force-frequency relationships in mammalian ventricular myocardium were studied in isolated papillary and ventricular muscle bundles. Tensions, velocities, and phase durations were determined from the isometric tension record and its first derivative. Decreasing bath temperature from 34–36°C to 27–31°C increased contractile tension and prolonged the phases of contraction in rat, guinea pig, and adult and fetal human tissues without altering the force-frequency relationship. Doubling extracellular [Ca++] beyond the 2.7 mM control for human tissue increased contractile tension and shortened phase I, and made the force-frequency relationship less steep or biphasic. These results suggest that the negative force-frequency relationship in the failing human heart cannot be explained merely on the basis on unavailability of Ca++ to the contractile proteins.
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| Type of Medium: |
Electronic Resource
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| URL: |