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Reproducibility of blood oxygen level-dependent signal changes with end-tidal carbon dioxide alterations

8 years 1 month ago
Hypercapnia has been utilized as a stimulus to elicit changes in cerebral blood flow (CBF). However, in many instances it has been delivered in a non-controlled method that is often difficult to reproduce. The purpose of this study was to examine the within- and between-visit reproducibility of blood oxygen level-dependent (BOLD) signal changes to an iso-oxic square wave alteration in end-tidal carbon dioxide partial pressure (P(et) CO(2) ). Two 3-Tesla (3T) MRI scans were performed on the same...
Donald R Dengel

Comparison of brachial dilatory responses to hypercapnia and reactive hyperemia

8 years 2 months ago
Flow-mediated dilation (FMD) relies on reactive hyperemia to stimulate the endothelium to release nitric oxide, causing smooth muscle relaxation. Hypercapnia also produces vasodilation, which is thought to be nitric oxide-independent. The purpose of this study was to compare and contrast the effects of hypercapnia and reactive hyperemia as stimuli for brachial artery dilation. On separate days, twenty-five participants underwent vasodilation studies via reactive hyperemia or hypercapnia (i.e. 10...
Justin R Geijer