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Contractile activity and fluorescence changes in fluo-3-loaded isolated ventricular myocytes
I Suetake1, H Takisawa, T Nakamura
1Department of Biology, Faculty of Science, Osaka University, Toyonaka, Japan.
The Japanese Journal of Physiology
|January 1, 1992
Summary
Researchers studied rat heart cells using fluo-3 to measure fluorescence and contraction. They found that isoproterenol increased cell activity, while BDM and low calcium reduced it by altering calcium transients and ATPase activity.
Area of Science:
- Cardiology
- Cell Physiology
- Biochemistry
Background:
- Isolated rat ventricular myocytes are a model for studying cardiac function.
- Fluo-3 is a fluorescent indicator used to measure intracellular calcium levels.
- Cardiac contractility is regulated by calcium transients and myofibrillar ATPase activity.
Purpose of the Study:
- To investigate the relationship between fluorescence changes and contractile parameters in isolated rat ventricular myocytes.
- To determine the effects of isoproterenol, 2,3-butanedione monoxime (BDM), and low extracellular calcium on cardiac myocyte function.
Main Methods:
- Isolated rat ventricular myocytes were loaded with the calcium indicator fluo-3.
- Fluorescence and contractile parameters were recorded simultaneously.
- Myocytes were exposed to isoproterenol, BDM, and a low calcium medium.
Main Results:
- Isoproterenol increased contractile activity by enhancing the calcium transient.
- BDM and low calcium medium suppressed contractile activity.
- BDM also decreased myofibrillar ATPase activity, contributing to suppression.
- Changes in beating activity correlated with variations in peak fluorescence intensity.
Conclusions:
- Fluo-3 loading did not impair myocyte beating activity.
- Cardiac myocyte contractility is modulated by calcium transients and myofibrillar ATPase activity.
- These findings provide insights into the mechanisms regulating cardiac contraction.