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Fluoroaluminate mimics agonist application in single rat hepatocytes
N M Woods1, C J Dixon, K S Cuthbertson
1Department of Human Anatomy and Cell Biology, University of Liverpool, U.K.
The Biochemical Journal
|January 15, 1990
Summary
Stimulating rat liver cells with agonists or fluoroaluminate caused calcium oscillations. Receptor-dependent agonists produced more regular calcium oscillations than direct G-protein activation, highlighting G-protein roles.
Area of Science:
- Cellular biology
- Biochemistry
- Physiology
Background:
- Cytosolic free calcium (Ca2+) levels are critical for cellular signaling.
- G-proteins play a key role in signal transduction pathways.
- Understanding calcium oscillations is essential for deciphering cellular responses.
Purpose of the Study:
- To investigate the generation of cytosolic free Ca2+ oscillations in rat hepatocytes.
- To compare the characteristics of Ca2+ oscillations induced by receptor-dependent agonists versus direct G-protein activation.
- To elucidate the role of G-proteins in generating repetitive Ca2+ oscillations.
Main Methods:
- Single rat hepatocytes were microinjected with the photoprotein aequorin.
- Hepatocytes were stimulated with glycogenolytic agonists or fluoroaluminate.
- Cytosolic free Ca2+ levels were measured by luminescence, detecting oscillations.
Main Results:
- Both stimulation methods induced Ca2+ oscillations, with levels rising from ~200 nM to over 600 nM.
- Oscillations generated by receptor-dependent agonists were more regular in frequency and time course.
- Direct G-protein activation via fluoroaluminate resulted in less regular oscillations.
Conclusions:
- G-proteins are involved in the generation of repetitive Ca2+ oscillations in hepatocytes.
- Receptor-mediated signaling provides a more regular pattern of Ca2+ oscillations compared to direct G-protein activation.
- The findings contribute to understanding the complex mechanisms of calcium signaling and G-protein function.