Adenine compounds: cerebrovascular effects in vitro with reference to their possible involvement in migraine.

Adenosine and adenine compounds (AMP, cyclic AMP, ADP and ATP) markedly dilated feline and human pial arteries in vitro, the effect being more prominent with increasing tone of the vessel (active tonic contraction induced by prostaglandin F 2 alpha or serotonin). In contrast, the various adenine compounds were unable to produce any dilation of extracranial arteries tested (branches of lingual, external maxillary, and superficial temporal arteries). The degree of dilatation depended upon the perivascular potassium concentration, so that low potassium increased Emax and reduced ED50 values. Possible involvement of adenine compounds in the vasodilatory phase of the migraine attack is discussed.