Remodelling of the heart in DOCA-salt hypertensive rats by propranolol and by an alpha-2 agonist, rilmenidine

Abstract

The effects of rilmenidine [(N-dicyclopropylmethyl) amino-2-oxazoline; S 3341], an alpha 2 agonist, on the hypertensive rat heart have been compared with those of propranolol, using a model of deoxycorticosterone acetate (DOCA)-salt hypertension. One week after nephrectomy and initial treatment with DOCA-salt, which was continued for an additional 7 weeks, the two drugs were added to the rats drinking water at a concentration of 10 mg/kg per day for rilmenidine and 15 mg/kg per day for propranolol. Both drugs had a slight and similarly significant antihypertensive effect at their respective concentrations [systolic blood pressure in controls, 141 +/- 15 mmHg (n = 20); after DOCA-salt, 209 +/- 22 mmHg (n = 24); after propranolol, 182 +/- 19 mmHg (n = 20, P less than 0.01); after rilmenidine, 192 +/- 15 mmHg (n = 19, P less than 0.05)]. They also lowered the systolic blood pressure x frequency product (P less than 0.001). Propranolol, but not rilmenidine, significantly reduced the left ventricular weight: body weight ratio [in controls, 2.00 +/- 0.2 mg/g; after DOCA-salt, 3.04 +/- 0.5 mg/g; after propranolol, 2.67 +/- 0.4 mg/g (P less than 0.05); after rilmenidine, 3.13 +/- 0.6 mg/g (P = NS)]. However, both propranolol and rilmenidine reduced left ventricular weight [in controls, 676 +/- 57 mg; after DOCA-salt, 827 +/- 114 mg; after propranolol, 732 +/- 108 mg (P less than 0.01); after rilmenidine, 760 +/- 100 mg (P less than 0.05)].(ABSTRACT TRUNCATED AT 250 WORDS)