the highest dose of ergotamine significantly reduced the shunting of the microspheres in the head.6 since 15 mum microspheres are only likely to reach the lungs by passing into the venous circulation through large glomus-type avas , we conclude that ergotamine reduces the fraction of microspheres appearing in the lungs by causing strong vasoconstriction in the avas in the head.7 in conformity with the closure of head avas is the finding that ergotamine reduced the jugular venous po ( 2 ) and o ( 2 ) saturation thereby increasing the a-v o ( 2 ) saturation difference.8 it is quite possible that decreased a-v shunting may be the prominent mechanism of the antimigraine action of the drug , since sudden opening of ava 's has been implicated in the pathophysiology of migraine-syndrome .
C0014710
ergotamine
C0149931
migraine-syndrome