INTRINSIC EFFECT OF ANTIHYPERTENSIVE TREATMENT WITH ISRADIPINE AND METOPROLOL ON LARGE ARTERY GEOMETRIC AND ELASTIC PROPERTIES

The effects of isradipine and metoprolol were studied on the brachial arteries of two groups of 14 patients with hypertension, 90 minutes af ter the first dose and after 3 months of treatment. Diameter (pulsed D oppler) and compliance (pulse-wave velocity) were measured and calcula ted in isobaric conditions by way of a model that allowed discriminati on of the active intrinsic drug action. Isradipine increased measured and isobaric diameter during short-term (p < 0.05) and long-term admin istration (p < 0.05), whereas metoprolol did not change it. Active dia meter effects were different between drugs during short-term administr ation (p < 0.05). Isradipine increased measured and isobaric complianc e during short-term (p < 0.05) and long-term administration (p < 0.05) . Short-term administration of metoprolol decreased measured complianc e (p < 0.01). Metoprolol decreased isobaric compliance during short-te rm (p < 0.01) and long-term (p < 0.05) administration. Active complian ce effects were different between drugs during short- and long-term ad ministration (p < 0.01). These arterial intrinsic drug effects, indepe ndent of the pressure-lowering influence, suggested different mechanis ms, consisting of a large artery smooth muscle relaxation for isradipi ne and an isometric arterial constriction for metoprolol.