Independent cerebral vasoconstrictive effects of hyperoxia and accompanying arterial hypocapnia at 1 ATA Export

@article{citeulike:3360882, abstract = {Breathing 100\% O2 at 1 atmosphere absolute (ATA) is known to be associated with a decrease in cerebral blood flow (CBF). It is also accompanied by a fall in arterial PCO2 leading to uncertainty as to whether the cerebral vasoconstriction is totally or only in part caused by arterial hypocapnia. We tested the hypothesis that the increase in arterial PO2 while O2 was breathed at 1.0 ATA decreases CBF independently of a concurrent fall in arterial PCO2. CBF was measured in seven healthy men aged 21-62 yr by using noninvasive continuous arterial spin-labeled-perfusion MRI. The tracer in this technique, magnetically labeled protons in blood, has a half-life of seconds, allowing repetitive measurements over short time frames without contamination. CBF and arterial blood gases were measured while breathing air, 100\% O2, and 4 and 6\% CO2 in air and O2 backgrounds. Arterial PO2 increased from 91.7 {+/-} 6.8 Torr in air to 576.7 {+/-} 18.9 Torr in O2. Arterial PCO2 fell from 43.3 {+/-} 1.8 Torr in air to 40.2 {+/-} 3.3 Torr in O2. CBF-arterial PCO2 response curves for the air and hyperoxic runs were nearly parallel and separated by a distance representing a 28.7-32.6\% decrement in CBF. Regression analysis confirmed the independent cerebral vasoconstrictive effect of increased arterial PO2. The present results also demonstrate that the magnitude of this effect at 1.0 ATA is greater than previously measured. 10.1152/japplphysiol.00303.2003}, author = {Floyd, Thomas F. and Clark, James M. and Gelfand, Robert and Detre, John A. and Ratcliffe, Sarah and Guvakov, Dimitri and Lambertsen, Christian J. and Eckenhoff, Roderic G.}, citeulike-article-id = {3360882}, citeulike-linkout-0 = {http://dx.doi.org/10.1152/japplphysiol.00303.2003}, citeulike-linkout-1 = {http://view.ncbi.nlm.nih.gov/pubmed/12937024}, citeulike-linkout-2 = {http://www.hubmed.org/display.cgi?uids=12937024}, day = {1}, doi = {10.1152/japplphysiol.00303.2003}, journal = {J Appl Physiol}, keywords = {asl, co2, healthy, hyperoxia, mri}, month = {December}, number = {6}, pages = {2453--2461}, posted-at = {2009-01-06 21:03:12}, priority = {0}, title = {Independent cerebral vasoconstrictive effects of hyperoxia and accompanying arterial hypocapnia at 1 ATA}, url = {http://dx.doi.org/10.1152/japplphysiol.00303.2003}, volume = {95}, year = {2003} }

TY - JOUR ID - citeulike:3360882 L3 - citeulike-article-id:3360882 N2 - Breathing 100% O2 at 1 atmosphere absolute (ATA) is known to be associated with a decrease in cerebral blood flow (CBF). It is also accompanied by a fall in arterial PCO2 leading to uncertainty as to whether the cerebral vasoconstriction is totally or only in part caused by arterial hypocapnia. We tested the hypothesis that the increase in arterial PO2 while O2 was breathed at 1.0 ATA decreases CBF independently of a concurrent fall in arterial PCO2. CBF was measured in seven healthy men aged 21-62 yr by using noninvasive continuous arterial spin-labeled-perfusion MRI. The tracer in this technique, magnetically labeled protons in blood, has a half-life of seconds, allowing repetitive measurements over short time frames without contamination. CBF and arterial blood gases were measured while breathing air, 100% O2, and 4 and 6% CO2 in air and O2 backgrounds. Arterial PO2 increased from 91.7 {+/-} 6.8 Torr in air to 576.7 {+/-} 18.9 Torr in O2. Arterial PCO2 fell from 43.3 {+/-} 1.8 Torr in air to 40.2 {+/-} 3.3 Torr in O2. CBF-arterial PCO2 response curves for the air and hyperoxic runs were nearly parallel and separated by a distance representing a 28.7-32.6% decrement in CBF. Regression analysis confirmed the independent cerebral vasoconstrictive effect of increased arterial PO2. The present results also demonstrate that the magnitude of this effect at 1.0 ATA is greater than previously measured. 10.1152/japplphysiol.00303.2003 IS - 6 JF - J Appl Physiol EP - 2461 TI - Independent cerebral vasoconstrictive effects of hyperoxia and accompanying arterial hypocapnia at 1 ATA VL - 95 SP - 2453 KW - asl KW - co2 KW - healthy KW - hyperoxia KW - mri AU - Floyd, Thomas AU - Clark, James AU - Gelfand, Robert AU - Detre, John AU - Ratcliffe, Sarah AU - Guvakov, Dimitri AU - Lambertsen, Christian AU - Eckenhoff, Roderic PY - 2003/12/01/ UR - http://dx.doi.org/10.1152/japplphysiol.00303.2003 ER -