EFFECTS OF PROLONGED IMMOBILIZATION OF THE LIMB ON RADIAL ARTERY MECHANICAL-PROPERTIES

Physical training is associated with an increase in arterial distensib ility. Whether the effect of training on this variable is evident also for ordinary levels of exercise or no exercise is unknown, however. W e have addressed this issue by investigating the effect on radial arte ry distensibility of prolonged monolateral immobilization of the ipsil ateral limb versus the following resumption of normal mobility. We stu died 7 normotensive subjects (age: 25.4+/-3.0 years; systolic/diastoli c blood pressure, 119+/-9/68+/-6 mm Hg, mean+/-SE) in whom 1 limb had been immobilized for 30 days in plaster because of a fracture of the e lbow. At both the day after plaster removal and after 45 days of rehab ilitation, radial artery distensibility was evaluated by an echo-crack ing device (NIUS-02), which allows arterial diameter to be measured no ninvasively and continuously over all pressures from diastole to systo le (finger monitoring), with the distensibility values being continuou sly derived from the Langewouters formula. In both instances, the cont ralateral arm was used as control. Immediately after removal of the pl aster, radial artery distensibility was markedly less in the previousl y immobilized and fractured limb compared with the contralateral limb (0.4+/-0.1 versus 0.8+/-0.1, 1/mmHg 10(-3), P<0.05). After rehabilitat ion, the distensibility of the radial artery was markedly increased in the previously fractured limb (0.65+/-0.1 l/mm Hg 10(-3), P<0.05), wh ereas no change was seen in the contralateral limb. Thus, complete int erruption of physical activity is associated with a marked reduction o f arterial distensibility, indicating that even an ordinary level of a ctivity plays a major role in modulation of arterial mechanical proper ties.