We used in vivo microdialysis to define the chronological relationship
between release of thromboxane and platelet activating factor (PAF) i
nto the extracellular space of ischemic hippocampus. The thromboxane l
evel peaked after 20 min of postischemic reperfusion, followed by a de
layed PAF response 120 min later. We conclude that cerebral ischemia c
auses delayed elevation of PAF in the extracellular space, long after
the immediate synthesis and release of thromboxane metabolites.