Hypercapnia primarily affects cerebral blood flow (CBF) and not cerebral me
tabolism. We compared the CBF responses due to electrical forepaw stimulati
on before and after brief hypercapnia in male, non-ovarectomized female, an
d ovarectomized female rats. Prior to hypercapnia the CBF responses were si
milar for all th ree groups. Seven minutes after brief hypercapnic exposure
the CBF responses to forepaw stimulation were augmented in all groups. How
ever, both 30 and 60 min after hypercapnia, the magnitude of the CBF respon
ses to forepaw stimulation remained elevated for males and ovarectomized fe
males, but not for non-ovarectomized females. These results suggest that es
trogen may modulate the upregulation of the CBF response observed after tra
nsient hypercapnia. (C) 2001 Elsevier Science Ireland Ltd. All rights reser
ved.