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MAP was modestly elevated across all time points during IH but only became elevated after 5 min during PH. During IH, V\u0304p was elevated from baseline throughout the exposure with a consistent hypoxic sensitivity of \u223c0.34 cm\u00b7s<jats:sup>\u22121<\/jats:sup>\u00b7%desaturation<jats:sup>\u22121<\/jats:sup>( P &lt; 0.05). The V\u0304p response to PH was biphasic with an initial decrease from baseline occurring at 79 \u00b1 23 s, followed by a subsequent elevation, becoming equivalent to the IH response by 10 min. The nadir of the PH response exhibited a hypoxic sensitivity of \u22120.24 cm\u00b7s<jats:sup>\u22121<\/jats:sup>\u00b7%desaturation<jats:sup>\u22121<\/jats:sup>. When expressed in relation to end-tidal Pco<jats:sub>2<\/jats:sub>, a sensitivity of \u22121.08 cm\u00b7s<jats:sup>\u22121<\/jats:sup>\u00b7Torr<jats:sup>\u22121<\/jats:sup>was calculated, similar to previously reported sensitivities to euoxic hypocapnia. Cerebrovascular resistance (CVR) was not changed during IH. During PH, an initial increase in CVR was observed. However, CVR returned to baseline by 20 min of PH. These data show the cerebrovascular response to PH consists of an early hypocapnia-mediated response, followed by a secondary increase, mediated predominantly by hypoxia.<\/jats:p>","DOI":"10.1152\/japplphysiol.00553.2007","type":"journal-article","created":{"date-parts":[[2007,10,26]],"date-time":"2007-10-26T15:19:30Z","timestamp":1193411970000},"page":"482-489","source":"Crossref","is-referenced-by-count":47,"title":["Cardiovascular and cerebrovascular responses to acute isocapnic and poikilocapnic hypoxia in humans"],"prefix":"10.1152","volume":"104","author":[{"given":"Craig D.","family":"Steinback","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marc J.","family":"Poulin","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"24","reference":[{"key":"R1","doi-asserted-by":"publisher","DOI":"10.3171\/jns.1982.57.6.0769"},{"key":"R2","doi-asserted-by":"publisher","DOI":"10.1152\/japplphysiol.01338.2006"},{"key":"R3","doi-asserted-by":"publisher","DOI":"10.1080\/00140130500101403"},{"key":"R4","doi-asserted-by":"publisher","DOI":"10.1152\/japplphysiol.01385.2003"},{"key":"R5","doi-asserted-by":"publisher","DOI":"10.1007\/BF02474565"},{"key":"R6","doi-asserted-by":"crossref","unstructured":"Asmussen E, Consolazio FC.The circulation in rest and work on Mount Evans.Am J Physiol132: 555\u2013563, 1941.","DOI":"10.1152\/ajplegacy.1941.132.2.555"},{"key":"R7","doi-asserted-by":"publisher","DOI":"10.1002\/jcu.1870150903"},{"key":"R8","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1967.23.2.183"},{"key":"R9","doi-asserted-by":"publisher","DOI":"10.1016\/j.pneurobio.2003.11.001"},{"key":"R10","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1986.60.4.1230"},{"key":"R11","doi-asserted-by":"crossref","unstructured":"De Burgh Daly M.Carotid bodies: \u201cprimary\u201d cardiovascular responses. 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