Regulation of blood pressure during long-term ouabain infusion in Long-Evans rats

We tested whether ouabain, an inhibitor of the sodium pump, can lead to chronic hypertension in Long-Evans rats using sensitive 24-h measurements of blood pressure. After a control week of vehicle isotonic saline infusion (14.4 mL/day), ouabain was infused intravenously at 30 μg/kg/day in intact (2K) and uninephrectomized (1K) Long-Evans rats for a total of 4 weeks. Although plasma ouabain concentration rose to 0.97 ± 0.15 nmol/L with ouabain infusion, mean arterial pressure did not change in either 2K (Δ = −0.6 ± 1.3 mm Hg) or 1K (Δ = −1.2 ± 0.7 mm Hg) rats. These data suggest that Long-Evans rats are insensitive to the hypertensive effects of ouabain.