Effects of indomethacin on cerebral blood flow at rest and during hypercapnia: An arterial spin tagging study in humans

Purpose: To investigate using an arterial spin tagging (AST) approach the effect of indomethacin on the cerebral blood flow (CBF) response to hypercapnia. Materials and Methods: Subjects inhaled a gas mixture containing 6% CO₂ for two 5-minute periods, which were separated by a 10-minute interval, in which subjects inhaled room air. In six subjects, indomethacin (i.v., 0.2 mg/ kg) was infused in the normocapnic interval between the two hypercapnic periods. Results: Indomethacin reduced normocapnic gray matter CBF by 36 ± 5% and reduced the CBF increase during hypercapnia from 43 ± 9% to 16 ± 5% in gray matter (P < 0.001) and from 48 ± 11% to 35 ± 9% in white matter (P < 0.025). Conclusion: The results demonstrate that an AST approach can measure the effects of indomethacin on global CBF increases during hypercapnia and suggest that an AST approach could be used to investigate pharmacological effects on focal CBF increases during functional activation.