Pindolol, not propranolol, reverses cardiac hypertrophy in renal hypertensive rats.

ABSTRACT

Reversal of cardiac hypertrophy has been obtained by treatment with some antihypertensive drugs but has not been achieved consistently with beta blockers. To investigate whether this difference might be explained by the distinct hemodynamic actions of the drugs, we studied the effects of propranolol and pindolol, beta blockers with distinct modes of action, on cardiac hypertrophy of hypertensive male Wistar rats, two-kidney, one clip (2K1C) Goldblatt model (n = 33) and sham-operated control rats (n = 34). We also assessed the effects of such therapies on the ventricular pumping ability during open-chest, transient aortic occlusion. Four weeks after surgery, propranolol (5 mg/kg/day p.o.) was given to hypertensive (n = 8) and control rats (n = 11); pindolol was also given orally (1 mg/kg/day) to similar groups (n = 7 and n = 5, respectively). Untreated animals served as controls for both groups. Cardiac hypertrophy developed with hypertension in the untreated rats of the propranolol (3.38 +/- 0.18 vs 2.60 +/- 0.08 mg/g; p less than 0.01) and pindolol groups (3.93 +/- 0.21 vs 2.40 +/- 0.03 mg/g; p less than 0.001). Treatment reversed cardiac hypertrophy in the pindolol-treated (3.01 +/- 0.19 vs 3.93 +/- 0.21 mg/g; p less than 0.001, NS) but not in the propranolol-treated rats (3.24 +/- 0.18 vs 3.38 +/- 0.21 mg/g, NS). The maximal pressure that developed during aortic occlusion in the propranolol group was similar to that observed in the pindolol group. These results indicate that cardiac hypertrophy is reversed by pindolol but not by propranolol, and that this reversal does not interfere with left ventricular pumping ability.