Life survival and cardiovascular structures following selective beta-blockade in spontaneously hypertensive rats.

The aim of this study was to assess life survival, and arterial and cardiac structural changes following chronic selective beta-blockade in spontaneously hypertensive rats (SHR). Twenty-two SHR aged 3 months and 20 SHR aged 18 months were treated with the beta 1-blocking agent bisoprolol (10 mg/kg/day) or placebo for a period of 2 months. At the end of this period left and right ventricular weight and morphometric parameters of five different arterial segments (thoracic and abdominal aorta, renal, mesenteric, and carotid arteries) were evaluated. In younger SHR, systolic blood pressure (tail-cuff method) was significantly lower in drug-treated animals (225 +/- 15 v 185 +/- 10 mm Hg in placebo-treated animals; P < .001); left ventricular weight was significantly lower in drug-treated rats (0.845 +/- 0.02 v 0.932 +/- 0.03 g; P < .05); medial thickness was significantly lower in the bisoprolol-treated rats at the site of the thoracic (-22%) and abdominal (-17%) aorta, and mesenteric artery (-29%); in the renal and carotid arteries, no change in medial thickness was observed. In older SHR, cardiovascular morbidity and mortality were significantly higher (P < .01) in the placebo group. In bisoprolol-treated animals, systolic blood pressure did not change and was even significantly higher than in controls. Heart weight and medial thickness of the thoracic aorta and the renal arteries were significantly lower in the Bisoprolol group. These results provide evidence that 2 months of selective beta-blockade in adult SHR has an important antihypertrophic cardiac and vascular effect.(ABSTRACT TRUNCATED AT 250 WORDS)