Related Experiment Videos
Fish antifreeze proteins block Ca entry into rabbit parietal cells
P A Negulescu1, B Rubinsky, G L Fletcher
1Department of Molecular and Cell Biology, University of California, Berkeley 94720.
The American Journal of Physiology
|December 1, 1992
Summary
Antifreeze proteins (AFPs) protect fish and insects from cold. New research shows AFPs also shield mammalian cells from hypothermic damage by blocking calcium ion entry, suggesting a broader role in cold tolerance.
Area of Science:
- Biochemistry
- Cell Biology
- Physiology
Background:
- Antifreeze proteins (AFPs) are known to prevent freezing in cold-adapted organisms.
- Recent findings suggest AFPs may also protect mammalian cells from hypothermic injury.
- Hypothermic damage is potentially linked to altered intracellular ion concentrations due to impaired active transport.
Purpose of the Study:
- To investigate if AFPs can reduce calcium ion (Ca) permeability in mammalian cells.
- To determine if AFPs affect calcium signaling pathways and active calcium transport.
Main Methods:
- Utilized rabbit gastric parietal cells, a well-characterized model for Ca transport.
- Employed digital image processing of the Ca-sensitive fluorescent indicator fura-2 to measure intracellular free Ca.
- Stimulated cells with carbachol to assess AFP effects on Ca entry, release, and efflux.
Main Results:
- AFPs inhibited passive Ca entry into rabbit gastric parietal cells during carbachol stimulation.
- AFP treatment did not disrupt Ca release from internal stores, indicating intact signaling.
- Active Ca efflux from the cells remained unaffected, confirming normal Ca pumping function.
Conclusions:
- AFPs reduce passive calcium ion permeability across mammalian cell membranes.
- This calcium-blocking action of AFPs may contribute to cold tolerance in animals.
- AFPs possess functions beyond ice recrystallization inhibition, including cellular protection at hypothermic temperatures.