The work presented here uses combined blood oxygenation level-dependent (BOLD) and arterial spin tagging (AST) approaches to study the effect of indomethacin on cerebral blood flow (CBF) and oxygen consumption (CMRO(2)) increases during motor activation. While indomethacin reduced the CBF increase during activation, it did not significantly affect the CMRO(2) increase during activation. The ratio of the activation-induced CBF increase in the presence and absence of indomethacin was 0.54 +/- 0.08 (+/-SEM, n = 8, P < 0.001), while the ratio of the CMRO(2) increase in the presence and absence of the drug was 1.02 +/- 0.08 (+/-SEM, N = 8, ns). Potential difficulties in estimating CMRO(2) changes from combined BOLD/AST data are discussed.