Influence of Clonidine (Catapressan®-ST155) on the Muscle Blood Flow in the Legs of Hypertensive Patients (Antagonism of Tolazoline)

Abstract

Using the Xenon133 local clearance technique, the influence of clonidine on the blood flow in the tibial anterior muscle of hypertensive patients was studied. Within 10 min after a single, slow intravenous injection of 0.15 mg clonidine, the mean blood pressure and the resting muscle blood flow decreased significantly, while the calculated resistance in this vascular bed tended to increase. During chronic oral administration of varying doses of clonidine, no significant changes were found in the muscle blood flow and vascular resistance at rest; however, determined after maximal ischemic exercise, the muscle blood flow was significantly decreased and the vascular resistance increased. Twenty mg tolazoline, injected intravenously in patients under chronic clonidine treatment, increase pulse rate and blood pressure but further decrease the resting muscle blood flow in the first 15 minutes after the injection.