Fig. 1.

Effect of nanomolar ouabain on Na-K-ATPase activity in kidney basolateral membranes (BLM). Sprague-Dawley rats, weighing 200–250 g, were treated for 4 days intraperitoneally with ouabain (1 μg·kg body wt⁻¹·day⁻¹). Kidneys were removed on day 4, decapsulated, and the cortex was carefully separated from the medulla. BLM were prepared from whole cortex as described in experimental procedures. Na-K-ATPase activity as ouabain (1 mM)-sensitive ATP hydrolysis was measured as described in experimental procedures. Values are means ± SE from BLM preparations from 8 separate animals (n = 8). All enzyme activity assays were run in triplicate; the values were averaged and considered as one value. *P < 0.05 by ANOVA followed by Bonferroni analysis.