Vol. 39 No. 2, 2000
Antagonizing Effects of Type I Antifreeze Protein on Ca++ Uptake in Fish TO-2 Cells
Ching-Feng Weng1, Hong-Yi Gong1, Jen-Leih Wu1, Choy-Leong Hew2 and Pung-Pung Hwang1,*
1Institute of Zoology, Academia Sinica, Taipei 115, Taiwan
2Department of Laboratory Medicine and Pathology, University of Toronto, Toronto, Ontario, M5G 1L5, Canada
Ching-Feng Weng, Hong-Yi Gong, Jen-Leih Wu, Choy-Leong Hew and Pung-Pung Hwang (2000)
The antifreeze proteins (AFPs) or glycoproteins in several species of
polar fish, which prevent the fish from being frozen in icy seawater,
have been suggested for use as cryoprotective agents. The present study
examines the effect of AFPs on Ca++ flux in a fish TO-2 cell line. The results indicate that type I AFP inhibits the uptake of Ca++ in a dose-dependent manner, but it does not antagonize the release of Ca++. By contrast, type III AFP shows no effect on Ca++ flux. The addition of calcium antagonists, La+++ (LaCl3), Co++ (CoCl2), or verapamil (L-type Ca++ channel blocker), to the uptake medium did not further enhance the blocking effect of AFP on Ca++ uptake, indicating that type I AFP is a non-selective Ca++ blocker.
Key words: Type I antifreeze protein, Ca++ blocker, Ca++ uptake, Ca++ release, Fish cell.
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