LAUSR

BACKGROUND AND AIMS The bi-directional association between hypertension and endothelial dysfunction (vicious cycle) is crucial for the development of cardiovascular disease. Since platelets and circulating CD34-positive cells have been reported to contribute to vascular repair (endothelial repair and the development of atherosclerosis), these two factors could act as an indicator for the activity of this vicious cycle. METHODS We conducted a cross-sectional study of 580 Japanese men aged 60-69 years who underwent an annual health check-up. Since aggressive endothelial repair might cause consumptive reduction of circulating CD34-positive cells, subjects were stratified by circulating CD34-positive count (<1.01 cells/μL or ≥ 1.01 cells/μL). RESULTS Platelet count is positively associated with hypertension among participants with a low CD34-positive cell count (multivariable-OR (odds ratio) for hypertension of 1 standard deviation (SD) increments in platelets (5.24 × 104/μL) = 1.47 (1.12, 1.91)), but not among participants with a high CD34-positive cell count (multivariable-OR = 0.91 (0.71, 1.18)). We also found that platelet count is positively associated with carotid intima-media thickness related to endothelial dysfunction among hypertensive participants with a low CD34-positive cell count (standardized parameter estimate (β) = 0.26, p = 0.008), but not with a high CD34-positive cell count (β = 0.11, p = 0.234). CONCLUSIONS Our results indicate that the number of platelets and circulating CD34-positive cells acts as an indicator of the activity of the vicious cycle that exists between hypertension and endothelial dysfunction in elderly Japanese men.