A time course of the changes in blood Ca2+ and freezing tolerance of Modiolus demissus (Dillwyn) demonstrated that increases in freezing tolerance parallel increases in blood Ca2+. The increases in freezing tolerance occurred rapidly, suggesting that Ca2+ affects freezing tolerance directly by its presence in the blood.
The presence of La3+ reduced the freezing tolerance of isolated foot muscle. Thus, Ca2+ appears to increase freezing tolerance directly by binding to cell membranes.
The loss of the contractile response of freeze-thawed foot muscle to Ach, KCl and caffeine and the continued response to CaCl2 suggested that cell membranes are the primary sites of freezing injury.
The increase in blood Ca2+ following low-temperature acclimation accounted for only 40% of the total change in freezing tolerance. Therefore, other mechanisms responsible for increasing the freezing tolerance of M. demissus following low temperature acclimation also exist.
A Calcium-Dependent Mechanism Responsible for Increasing the Freezing Tolerance of the Bivalve Mollusc Modiolus Demissus
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DENNIS J. MURPHY; A Calcium-Dependent Mechanism Responsible for Increasing the Freezing Tolerance of the Bivalve Mollusc Modiolus Demissus. J Exp Biol 1 August 1977; 69 (1): 13–21. doi: https://doi.org/10.1242/jeb.69.1.13
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