[Vasoselective, substance-specific actions of isradipine on the great arteries of hypertensives in comparison to metoprolol].

The effects of isradipine (Lomir, CAS 75695-93-1) and metoprolol (CAS 37350-58-6) on geometry and arterial compliance of the arteria brachialis of 14 patients each with essential hypertension were compared acutely and after three months of therapy by means of pulsed Doppler sonography and the determination of pulse wave velocity. A calculation model was used that allowed to determine the drug-specific effects on arterial diameter and compliance under isobaric conditions. Isradipine increased measured and isobaric diameter during short-term (p < 0.05) and long-term administration (p < 0.05) whereas metoprolol did not change it. Isradipine increased measured and isobaric compliance during short-term (p < 0.05) and long-term administration (p < 0.05). Metoprolol reduced measured compliance acutely (p < 0.01) and isobaric compliance acutely (p < 0.05) and long-term (p < 0.05). Drug-specific effects on compliance were different during short-term and long-term administration (p < 0.01); the diameter was influenced differently only during short-term administration (p < 0.05). These opposite drug effects on the A. brachialis are probably due to a vasoselective relaxation of smooth muscle in large arteries by isradipine and-in the case of metoprolol-arterial constriction. The increase of arterial compliance by isradipine reduces very effectively the load on the heart and could form the basis for the improvement in the prognosis of the hypertensive patient.