Bedrest increases pressure distension in arteries, arterioles and veins of the leg. We hypothesized that bedrest-induced deconditioning of leg vessels is governed by the removal of the local increments in transmural pressure induced by assuming erect posture, and therefore can be counteracted by intermittently increasing local transmural pressure during the bedrest. Ten men underwent 5 weeks of horizontal bedrest. A subatmospheric pressure (-90 mmHg) was intermittently applied to one lower leg (pressure habituation, PH leg). Vascular pressure distension was investigated before and after the bedrest, both in the PH and control (CN) leg by increasing local distending pressure, stepwise up to +200 mmHg. Vessel diameter and blood flow were measured in the posterior tibial artery and vessel diameter in the posterior tibial vein. In the CN leg, bedrest lead to 5-fold and 2.7-fold increments (p<0.01) in tibial artery pressure-distension and flow responses, respectively, and to a 2-fold increase in tibial vein pressure distension. In the PH leg, arterial pressure-distension and flow responses were unaffected by bedrest, whereas bedrest lead to a 1.5-fold increase in venous pressure distension. It thus appears that bedrest-induced deconditioning of leg arteries, arterioles and veins, is caused by removal of gravity-dependent local pressure loads, and may be abolished or alleviated by a local pressure-habituation regimen.
- arterial stiffness
- venous compliance
- vascular remodeling
- Copyright © 2015, Journal of Applied Physiology