Action of Aldosterone and Ouabain on O 2 Consumption and Short-Circuit Current of Toad Bladder ∗

Abstract

Summary

O₃ consumption of minced urinary bladders of toads which were kept in various environments was measured. A concentration of aldosterone (1.9 × 10⁻⁷ M) effective in increasing Na+ transport was found to produce a significant increase in O₂ uptake in a glucose-enriched media using bladders from toads kept in a distilled water environment. This stimulant effect was less apparent in bladders from toads kept in a moist soil environment. The stimulation of O₂ consumption by aldosterone seen in bladders from toads kept in distilled water was non-linear, with 2 rates being distinguishable, one from 0-150 minutes, the other from 150 minutes on. This change in rate of O₂ consumption may be related to the latent period for stimulation of enzyme synthesis and active Na⁺ transport suggested by others. Ouabain was found to produce no significant effect on O₂ consumption of minced bladders. Ouabain (8.3 × 10⁻⁵ M) produces only a transient decrease in the short-circuit current of the isolated toad bladder. This is in marked contrast to the potent inhibition produced by the glycoside in frog skin. Although O₂ uptake of tissue in high (18.8 mEq) K⁺ media was significantly higher than that seen in a normal (1.88 mEq) solution, steroid effects were absent in the high K⁺ environment. The data are compatible with the view that aldosterone produces its effect on active Na⁺ transport in part via an effect on O₂-depen-dent energy metabolism.