The effect of intra-arterial injections of hydergine and dihydroergocornine on the peripheral circulation in man.

If given by the intra-arterial route, the immediate effect of the hydrogenated alkaloids of ergot is unpredictable. Vasodilation is obtained in some patients only. However, it was found that in those cases who do not react, the vessels respond more easily to the release of sympathetic tone, proving that, nevertheless, the drug has had an (potential) effect, probably on the neurovascular apparatus. This effect could be demonstrated for many hours and is, therefore, of considerable therapeutic interest. Even with the higher local concentrations possible by the intra-arterial route, the hydrogenated alkaloids of ergot still did not exhibit any adrenolytic action on the peripheral blood vessels in man.