The role of the neuropeptide substance P (SP) in the control of dural
arterial blood flow was examined in barbiturate-anaesthetised rats. Th
e parietal skull was trephinised and the blood flow in branches of the
medial meningeal artery was monitored with a laser Doppler flowmeter.
Electrical stimulation of the dura mater encephali at a parasagittal
site with pulses of 0.5 ms (10-20 V, 5-10 Hz, 30 s) caused a transient
increase in dural blood flow which was reproducible in size with repe
titive stimulation. Neither the basal flow nor the stimulus-evoked flo
w was significantly changed by topical administration of SP, the SP an
alog septide, or the NK1 antagonist RP 67580. It is concluded that SP
released from dural nerve fibres upon local stimulation does not play
an important role in the regulation of dural arterial flow.