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Open Access Research article

Effect of prolonged standardized bed rest on cystatin C and other markers of cardiovascular risk

Karin Arinell1*, Kjeld Christensen1, Stéphane Blanc2, Anders Larsson3 and Ole Fröbert1

Author Affiliations

1 Department of Cardiology, Örebro University Hospital, Örebro, Sweden

2 Institut Pluridisciplinaire Hubert Curien-De'partement d'Ecologie, Physiologie, Ethologie Unite' Mixte de Recherche 7178. Centre National de la Recherche Scientifique, Universite' de Strasbourg, Strasbourg, France

3 Department of Medical Sciences, Clinical Chemistry, Uppsala University, Uppsala, Sweden

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BMC Physiology 2011, 11:17  doi:10.1186/1472-6793-11-17

Published: 9 December 2011

Abstract

Background

Sedentary lifestyle is associated with coronary artery disease but even shorter periods of physical inactivity may increase cardiovascular risk. Cystatin C is independently associated with cardiovascular disease and our objective was to investigate the relation between this novel biomarker and standardized bed rest. Research of immobilization physiology in humans is challenging because good biological models are in short supply. From the Women International Space simulation for Exploration study (WISE) we studied markers of atherosclerosis and kidney function, including cystatin C, in a standardized bed rest study on healthy volunteers. Fifteen healthy female volunteers participated in a 20-day ambulatory control period followed by 60 days of bed rest in head-down tilt position (-6°) 24 h a day, finalized by 20 days of recovery. The subjects were randomized into two groups during bed rest: a control group (n = 8) that remained physically inactive and an exercise group (n = 7) that participated in both supine resistance and aerobic exercise training.

Results

Compared to baseline values there was a statistically significant increase in cystatin C in both groups after bed rest (P < 0.001). Glomerular filtration rate (GFR), calculated by both cystatin C and Cockcroft-Gault equation, decreased after bed rest while there were no differences in creatinine or creatine kinase levels. CRP did not change during bed rest in the exercise group, but there was an increase of CRP in the control group during recovery compared to both the baseline and the bed rest periods. The apo-B/apo-Ai ratio increased during bed rest and decreased again in the recovery period. Subjects experienced a small but statistically significant reduction in weight during bed rest and compared to baseline weights remained lower at day 8 of recovery.

Conclusion

During and following prolonged standardized bed rest the concentrations of several clinically relevant cardiovascular risk markers change.