Circulating angiogenic cell population responses to 10 days of reduced physical activity.

Circulating angiogenic cells (CACs) are a diverse group that have been identified as predictors of cardiovascular health and are inversely proportional to cardiovascular disease (CVD) outcomes. Inactivity is a growing concern in industrialized nations and is an independent risk factor for CVD. There is limited evidence regarding the impact of reduced physical activity (rPA) on different CAC populations. The purpose of this study was to evaluate the effect of objectively monitored rPA with maintained energy balance on two CAC populations (CFU and CD34(+) cells), intracellular nitric oxide (NOi), and genes related to NO production in active, healthy men. Participants (age 25 ± 2.9 yr) refrained from structured physical activity for 10 days, which was reflected by a significant reduction in time in vigorous + very vigorous intensity activity (P = 0.03). Sedentary time tended to increase (P = 0.06) with rPA. CFU CACs have been characterized as mainly monocytic and lymphocytic cells. We found significant reductions in both the number of CFU CACs (-35.69%, P = 0.01) and CFU CAC NOi (-33.84%, P = 0.03). Neither NOi nor the number of CD34(+) cells, which are hematopoietic and endothelial progenitors, changed with rPA. We found no significant differences in NO-related gene expression or oxidative stress-related gene expression with rPA in either CAC type. Therefore, we conclude that although various CAC populations have been related to vascular health, regular physical activity is necessary to maintain CAC NOi and the vulnerability of CACs to short-term reductions in physical activity is population specific.