{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,5]],"date-time":"2026-10-05T17:52:44Z","timestamp":1791222764191,"version":"4.1.0"},"reference-count":20,"publisher":"American Physiological Society","issue":"9","funder":[{"DOI":"10.13039\/501100000024","name":"Canadian Institute of Health Research","doi-asserted-by":"crossref","award":["217532"],"award-info":[{"award-number":["217532"]}],"id":[{"id":"10.13039\/501100000024","id-type":"DOI","asserted-by":"crossref"}]},{"name":"Canadian Institute of Health Research Doctoral scholarship"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["American Journal of Physiology-Heart and Circulatory Physiology"],"published-print":{"date-parts":[[2015,5,1]]},"abstract":"<jats:p> This study compared changes in cross-sectional area (CSA) and flow (Q) between the middle cerebral artery (MCA) and the internal carotid artery (ICA) at baseline and during 5 min of hypercapnia (HC; 6% CO<jats:sub>2<\/jats:sub>) and hypocapnia (HO; hyperventilation) and quantified how these changes contribute to estimates of cerebrovascular reactivity (CVR). Measures of MCA CSA were made using 3T magnetic resonance imaging. On a separate day, MCA flow velocity was measured with transcranial Doppler ultrasound and ICA diameters and flow velocity were measured with duplex ultrasound. Fourteen subjects (23 \u00b1 3 yr, 7 females) participated, providing data for 11 subjects during HC and 9 subjects during HO. An increase in MCA CSA ( P &lt; 0.05) was observed within the first minute of HC. During HO, the decrease in MCA CSA ( P &lt; 0.05) was delayed until minute 4. No changes were observed in ICA CSA during HC or HO. The relative changes in Q<jats:sub>ICA<\/jats:sub> and Q<jats:sub>MCA<\/jats:sub> were similar during HC and HO. Therefore, the MCA, but not ICA, dilates and constricts during 5 min of HC and HO, respectively. The consequent impact on Q<jats:sub>MCA<\/jats:sub> significantly affects estimates of CVR, and reactivity cannot be attributed solely to changes in smaller arterioles. <\/jats:p>","DOI":"10.1152\/ajpheart.00761.2014","type":"journal-article","created":{"date-parts":[[2015,2,27]],"date-time":"2015-02-27T23:20:10Z","timestamp":1425079210000},"page":"H1030-H1038","source":"Crossref","is-referenced-by-count":76,"title":["Heterogeneous patterns of vasoreactivity in the middle cerebral and internal carotid arteries"],"prefix":"10.1152","volume":"308","author":[{"given":"Nicole S.","family":"Coverdale","sequence":"first","affiliation":[{"name":"Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada; and"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sophie","family":"Lalande","sequence":"additional","affiliation":[{"name":"Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada; and"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Amanda","family":"Perrotta","sequence":"additional","affiliation":[{"name":"Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada; and"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"J. 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