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 chr onic hypertension in Long-Evans rats using sensitive 24-h measurements of b lood pressure. After a control week of vehicle isotonic saline infusion (14 .4 mL/day), ouabain was infused intravenously at 30 mu g/kg/day in intact ( 2K) and uninephrectomized (1K) Long-Evans rats for a total of 4 weeks. Alth ough plasma ouabain concentration rose to 0.97 +/- 0.15 nmol/L with ouabain infusion, mean arterial pressure did not change in either 2K (Delta = -0.6 +/- 1.3 mm Hg) or 1K (Delta = -1.2 +/- 0.7 mm Hg) rats. These data suggest that Long-Evans rats are insensitive to the hypertensive effects of ouabai n. (C) 1999 American Journal of Hypertension, Ltd.