Temperature compensation of sodium transport and ATPase activity in frog skin

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Abstract
Na+ transport across frog skin, measured as short-circuit current (SCC) shows perfect temperature compensation in frogs acclimated to 6.degree., 12.degree. and 23.degree. C as SCC values observed at the acclimination temperatures are equal (.apprx. 13 .mu.A/cm2). Reacclimation experiments show that this is not a starvation effect. While very little temperature compensation is seen in the activity of Na+,K+- ATPase in epidermal homogenates from frog skins, the activity of Mg2+-ATPase shows inverse compensation at assay temperatures from 4-48.degree. C. This ATPase is apparently activated by Mg2+ or by Ca2+ and it probably controls the passive permeability of epidermal cells. The inverse temperature compensation in the activity of this enzyme may be the main mechanism by which the observed perfect temperature compensation of Na+ transport across frog skin occurs.