Reductions in Basal Blood Flow and Arterial Remodeling after Short-Term Leg Immobilization

Abstract

0375 PURPOSE: We tested the hypothesis that short-term immobilization of leg with casting would reduce basal leg blood flow and vascular conductance and induce structural alterations in femoral artery. METHODS: Right knee and ankle joints of 8 young healthy men (22 ± 1 yr) were immobilized with casting for 7 days. Before, immediately after, and 14 days after the immobilization, femoral artery function and structure were measured using a duplex ultrasound. RESULTS: Arterial blood pressure and leg circumference did not change throughout the study. Femoral artery lumen diameter in the immobilized leg decreased after the immobilization (p < 0.05) and returned to baseline during the recovery period, in which the subjects did not receive any rehabilitation treatment. Femoral artery intima-media thickness (IMT) and IMT/lumen ratio in both legs did not show significant changes throughout the interventions. In the immobilized leg, femoral artery blood flow and vascular conductance decreased (−23 to 24%) after the immobilization (all p < 0.05). These parameters returned to the baseline during the recovery period, and there were no significant differences between the baseline and recovery values. In the control leg, femoral blood flow, vascular conductance, and vascular resistance did not change throughout the investigation. After 7 days of casting, femoral arterial expansion rate, an index of arterial distensibility, tended to decrease in the immobilized leg but not in the control leg. CONCLUSION: A short-term immobilization of lower limb decreases basal limb blood flow and induces inward, eutrophic remodeling. These results suggest that disuse-induced reductions in blood flow may occur prior to muscle atrophy and that basal limb blood flow may be modulated by an ordinary level of physical activity.