Ion transport and respiration of isolated frog skin

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Abstract
Simultaneous measurements of active ion transport and O2 consumption were made on the isolated frog skin. The short-circuit current was used as the measure of ion transport (Ussing and Zerahn, 1951) and O2 consumption was measured polarographically with vibrating platinum micro-electrodes. The ratio of the number of Na ions transported per molecule of O2 consumed ranged from 2 to 13 (120 periods of measurement) with a mean of 6.82 and a standard error of the mean of [plus or minus] 0.61. In all but 5 periods the value of this ratio was above 4. These results invalidate for frog skin the "redox" hypothesis of active ion transport as formulated by Conway (1953, 1954, 1955) and Lundegardh (1954) according to which no more than 4 univalent ions can be transported per molecule of O2 consumed. Crude neurohypophyseal preparations which are known to augment the active transport of Na by the isolated frog skin are shown to increase O2 uptake by about 20%. Both pure oxytocin and pure vasopressin similarly increase ion transport and O2 consumption by this tissue.