Regression of structural cardiovascular changes by antihypertensive therapy in spontaneously hypertensive rats.

Trophic adrenergic influences may in part potentiate the pressure dependent development of structural cardiovascular changes in hypertension. Regression of such changes by antihypertensive treatment should therefore be most successful if adrenergic blocking drugs are used. In the present study spontaneously hypertensive rats (SHR) received either alpha-methyldopa, metoprolol, felodipine, a new vasodilating Ca2+-antagonist, or metoprolol and felodipine in combination for 10 weeks. Their left ventricles were weighed and resistance vessel design was analysed using a haemodynamic technique. Arterial pressure (MAP) was equally reduced by metoprolol and felodipine. Despite their different modes of action cardiovascular design was also equally affected. The combined regimen reduced average MAP more than either drug alone. It also caused more pronounced regression of cardiovascular structural changes. Methyldopa lowered MAP less than either metoprolol or felodipine and had only modest effects on cardiovascular design. Thus, the extent of MAP reduction, regardless of which therapeutic regimen is used to induce it, determines the extent of regression of structural cardiovascular changes during antihypertensive treatment.