A comparative plethysmographic study of the venoconstrictor effect of dihydroergotamine and dihydroergotoxine on the deep veins of the calf in healthy subjects and patients suffering from varicosis.

The venoconstrictor effect of dihydroergotamine and dihydroergotoxine was compared in ten volunteers and in tne patients suffering from varicosis of the leg veins. The dihydrogenated ergot alkaloids were administered subcutaneously in a dose of 0.5 mg each. The influence on the capacitance reaction was determined by occlusion plethysmography of the calf. In addition, the arterial resistance was measured in the same region. Dihydroergotamine reduces the capacitance reaction in volunteers only at the high occlusion pressure levels 8.0 and 10.7 kPa after a lag of 40 min, whereas dihydroergotoxine does not show any significant influence. On the other hand, dihydroergotamine and dihydroergotoxine lead to a significant decrease in capacitance reaction in the patients after 20 and 60 min, respectively. However, the effect if dihydroergotamine (2.1 ml/100 ml tissue) is significantly greater than that of dihydroergotoxine (1.2 ml/100 ml tissue) and nearly normalizes the increased capacitance reaction. The two drugs increase the arterial resistance more clearly in the volunteers than in the patients, and dihydroergotoxine more often than dihydroergotamine tends to decrease resistance when the pre-existent resistance value is low.