Open AccessCerebrovascular regulation in men and women: stimulus‐specific role of cyclooxygenase
Author(s) -
Peltonen Garrett L.,
Harrell John W.,
Rousseau Cameron L.,
Ernst Brady S.,
Marino Mariah L.,
Crain Meghan K.,
Schrage William G.
Publication year - 2015
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.12451
Subject(s) - cyclooxygenase , stimulus (psychology) , medicine , neuroscience , bioinformatics , chemistry , biology , psychology , biochemistry , enzyme , cognitive psychology
Abstract Greater cerebral artery vasodilation mediated by cyclooxygenase ( COX ) in female animals is unexplored in humans. We hypothesized that young, healthy women would exhibit greater basal cerebral blood flow ( CBF ) and greater vasodilation during hypoxia or hypercapnia compared to men, mediated by a larger contribution of COX . We measured middle cerebral artery velocity ( MCA v, transcranial Doppler ultrasound) in 42 adults (24 women, 18 men; 24 ± 1 years) during two visits, in a double‐blind, placebo‐controlled design ( COX inhibition, 100 mg oral indomethacin, Indo). Women were studied early in the follicular phase of the menstrual cycle (days 1–5). Two levels of isocapnic hypoxia ( S P O 2 = 90% and 80%) were induced for 5‐min each. Separately, hypercapnia was induced by increasing end‐tidal carbon dioxide ( PET CO 2 ) 10 mmHg above baseline. A positive change in MCA v (Δ MCA v) reflected vasodilation. Basal MCA v was greater in women compared to men ( P < 0.01) across all conditions. Indo decreased baseline MCA v ( P < 0.01) similarly between sexes. Hypoxia increased MCA v ( P < 0.01), but Δ MCA v was not different between sexes. Indo did not alter hypoxic vasodilation in either sex. Hypercapnia increased MCA v ( P < 0.01), but Δ MCA v was not different between sexes. Indo elicited a large decrease in hypercapnic vasodilation ( P < 0.01) that was similar between sexes. During the early follicular phase, women exhibit greater basal CBF than men, but similar vasodilatory responses to hypoxia and hypercapnia. Moreover, COX is not obligatory for hypoxic vasodilation, but plays a vital and similar role in the regulation of basal CBF (~30%) and hypercapnic response (~55%) between sexes.