Effect of Ca2+ on the cryoprotective action of trehalose.

The competitive effect of Ca2+ on the cryoprotective action of carbohydrates has been investigated during freeze-thaw processes of unilamellar egg phosphatidylcholine vesicles. Ca2+ inhibits the cryoprotection achieved by trehalose to a greater extent than other sugars such as galactose, sucrose, and fructose. The cryoprotection by trehalose is also dependent on the Ca2+ concentration in the inside solution of the vesicle, even in the absence of external Ca2+. The competitive effect of Ca2+/trehalose is interpreted as a consequence of the different amount of interfacial water displaced by each compound in their adsorption on the water/lipid interface.