1e:T40d,Studies on man and lower animals have shown that the cranial blood vessels are pain-sensitive structures, capable under special circumstances of giving rise to headache.¹The distention of cerebral arteries is primarily responsible for the headache produced by certain chemical agents, of which histamine is representative;²the headache associated with septicemia and fever is in the same category.³It has been shown that the afferent fibers from the pain-sensitive cerebral arteries above the tentorium enter the brain stem primarily through the fifth cranial nerve, whereas the fibers from the arteries below the tentorium enter the nervous system chiefly through the upper cervical nerves.⁴The distention of certain branches of the external carotid arteries is chiefly responsible for migraine headache and the headache associated with arterial hypertension.⁵ Thus, data about the great variety of headaches resulting from distention of cranial arteries are specific, but there is1f:T4de,1. The dura mater encephali of the rat was exposed and the blood flow around branches of the medial meningeal artery was monitored with a laser Doppler flowmeter. Changes in the meningeal blood flow (MBF) following electrical stimulation of the dura mater at a parasagittal site were registered. The effects of human calcitonin gene-related peptide (h-alpha CGRP) and the CGRP antagonist (h-alpha CGRP8-37) on the MBF were tested. 2. Electrical stimulation with rectangular pulses of 0.5 ms, 10-20 V, 5-10 Hz and a duration of 30 s caused an increase of the MBF in 14 out of 16 rats tested. The increases were dependent on stimulus strength and frequency. 3. The increase in MBF was inhibited in a dose-dependent manner by topical application of 0.1 ml of h-alpha CGRP8-37 at concentrations of 10(-7) - 10(-5) M. The highest dose abolished the increase in MBF. 4. Topical administration of 0.1 ml of h-alpha CGRP at a concentration of 10(-4) M increased the basal MBF by 15% on average. 5. It is suggested that the increase in MBF following electrical stimulation of the dura mater is mediated by the release of CGRP. The contribution of the dural afferent and sympathetic and parasympathetic efferent nerve fibres to this response are discussed.20:Tbc2,

	Year	Citations

References