title: Reply to Pancheva, Panchev, and Pancheva.
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Zuj
authors.forename: Richard L
authors.initials: RL
authors.lastname: Hughson
mesh_terms: D001794:Blood Pressure; D002245:Carbon Dioxide / Q000097:blood*; D002536:Cerebral Arteries / Q000503:physiopathology*; D002560:Cerebrovascular Circulation; D006801:Humans; D008297:Male; D054971:Orthostatic Intolerance / Q000209:etiology*; D013575:Syncope / Q000209:etiology*; D014661:Vasoconstriction
chemical_list: D002245:Carbon Dioxide