[Effect of ergot alkaloids on venous tonus determined in superficial hand veins in situ].

The venoconstrictor effect of dihydroergotamine in man was demonstrated by Rieckert and Pauschinger in 1967. In a study on the influence of local infusions of dihydroergotamine into superficial hand veins in man we found a direct venoconstrictor effect of the drug. In further studies the effects of dihydroergotamine were compared with those of other dihydrogenated and non-dihydrogenated ergot alkaloids and a dose-dependent venoconstrictor effect was observed after local infusion of dihydroergotamine, dihydroergostine, dihydroergovaline, ergotamine and methysergide into superficial hand veins in man. Dihydroergotamine was weight for weight somewhat less active than ergotamine. But as Mellander and Nordenfelt have shown that dihydroergotamine elicits only a weak effect on resistance vessels, this drug seems for the treatment of orthostatic hypotension to be preferable to ergotamine for which Owen and Stürmer have demonstrated a marked constriction of resistance vessels in the skin. Experiment with dihydroergotamine showed that the venoconstriction in these human veins is mainly due to alpha-adrenoceptor stimulation. As in the treatment of orthostatic hypotension drugs are usually given in oral form, the activity of dihydroergotamine was also investigated after oral administration and the venoconstrictor activity confirmed.