tokens: Six weeks after clipping of one renal artery , hypertensive rats ( 178 +/- 4 mm Hg ) were randomly assigned to three groups : untreated hypertensive controls ( n = 8 ), enalapril - treated ( n = 8 ), or nitrendipine - treated ( n = 10 ). Sham - operated rats served as normotensive controls ( 128 +/- 3 mm Hg , n = 8 ). After 6 weeks of treatment , renal hemodynamics ( glomerular filtration rate and renal plasma flow ) were measured in the anesthetized rats .