[Acute changes in intracerebral vascular resistance after application of dihydrogenated ergot alkaloids (author's transl)].

Measurements of total cerebrovascular resistance (CVR) before and after administration of dihydrogenated ergot alkaloids are performed using a decoupling extracorporeal bypass system in rabbits. From the experiments there is clear evidence that the application of dihydroergotoxine-mesylate (28 micrograms/ml intracarotid.) or dihydroergocristine-methansulfonate (Decme, DHEC, 27 micrograms/ml) is followed by a significant drop in total CVR during 5--6 min. In addition, DHEC shows other, more differentiated effects within the cerebrovascular system. At comparable concentrations within the cerebrovascular system, the vasodilatory effect of DHEC seems to be a function of the initial CVR before administration of the drug (range of the initial CVR-values: 1.1--2.0 kPa-min/ml). During very low initial CVR-values (CVR less than 1.1. kPa-min/ml) the application of DHEC is followed by an increase in CVR. There are indications that DHEC acts as a vasoconstrictor in the cerebral vascular bed if the initial CVR-values are quite low. This bivalent effect of DHEC on CVR may cause favourable redistributions of regional blood flow under certain circumstances (e.g., if focal hypoperfusion is combined with perifocal hyperemia).