Role of prostaglandins in the response of the cerebral circulation to carbon dioxide in conscious rabbits.

The role of prostaglandins in maintenance of resting cerebral blood flow (CBF) and in cerebral vaso­ dilatation during hypercapnia remains controversial. The effect of indomethacin, a cyclo-oxygenase inhibitor, on CBF and cerebrovascular resistance (CVR) was exam­ ined in conscious animals. Regional and total CBF were measured with radioactive microspheres, and the efficacy of blockade of prostaglandin synthesis by indomethacin was examined by the cranial window method. CBF was measured in conscious rabbits with 15-lLm radioactive mi­ crospheres during normocapnia (Peo2 = 30 mm Hg) and hypercapnia (Peo2 = 60 mm Hg), before and after intra­ venous administration of indomethacin (10 mg/kg) or ve­ hicle (n = 6 for each). Thus, each animal served as its own control. CBF was 84 ± 6 and 190 ± 27 (mean ± SE) mllmin/lOO g during normocapnia and hypercapnia, respectively, before indomethacin, and 78 ± 5 mllmin/l00 g during normocapnia and 180 ± 16 mllmin/lOO g during hypercapnia following indomethacin. Thus, indomethacin