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Evidence implicating a membrane ATPase in the control of passive permeability of excitable cells
Author(s) -
Bowler K.,
Duncan C. J.
Publication year - 1967
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1040700116
Subject(s) - atpase , arrhenius equation , enzyme , permeability (electromagnetism) , chemistry , biophysics , crayfish , membrane permeability , biochemistry , biology , membrane , ecology , activation energy , organic chemistry
The temperature sensitivity of the ATPase enzyme systems in a muscle microsomal preparation from the crayfish, Astacus pallipes , was studied. Preincubation of the enzyme preparation in the range 33–36°C produced a marked inactivation of the ATPases; the Mg ++ ‐dependent ATPase was very much more sensitive to this treatment than the Na + ‐K + ‐Mg ++ ‐dependent ATPase. Thus, the Arrhenius μ for the inactivation of the Mg ++ ‐dependent ATPase produced by eight minute preincubation is > 100 Kcals. These results are compared with the changes that are observed during the heat death of the whole animal, where exposure to 35°C produces a dramatic change in Na + permeability within five minutes. Arrhenius μ for heat death is also > 100 Kcals and operates over the identical critical temperature range. It is suggested that the Mg ++ ‐dependent ATPase controls passive permeability in these excitable cells and the results also confirm the view that Mg ++ and Na + ‐K + ‐Mg ++ ATPases are separate enzymes.