Fig. 4. Plasma concentrations of (A) K⁺ and (B) Na⁺ in controls, after 2 h anoxia and after exhaustive exercise in leopard frogs at 15°C. Values are means ± S.E.M., N=5 per treatment for each ion. Differences between treatments are indicated by differing letters (LSM, Student's post-hoc t-test).