Prostaglandin inhibition causes an increase in reactive hyperaemia after ischaemic exercise in human forearm

The hypothesis that prostaglandins contribute to the reactive hyperaemia af ter 5 min of ischaemia or 5 min of ischaemic exercise was investigated in s ix men by inhibiting prostaglandin production with ibuprofen (1800 mg) and indomethacin (225 mg) over 24 h before testing. Blood flow was measured con tinuously in the baseline and after ischaemia by combined pulsed and echo D oppler as the product of velocity and cross-sectional area. After 5 min of ischaemia, there were no differences in blood flow between placebo and the two drug conditions, except at 5 and 10 s when flow with indomethacin was g reater than both placebo and ibuprofen. After 5 min of ischaemic exercise, blood flow was significantly greater as a consequence of increased vascular conductance in each of ibuprofen and indomethacin than placebo from 5 unti l 90 s of recovery. We conclude that prostaglandin inhibition had little or no effect on reactive hyperaemia after 5 min of circulatory occlusion alon e,but that blood flow after ischaemic exercise was elevated due to increase d vascular conductance when prostaglandin synthesis was inhibited.