Dihydroergotamine decreases the blood content in the skeletal musculature but etilefrine hydrochloride in the splanchnic region in man.

Dihydroergotamine (DHE, Dihydergot) constricts the capacitance vessels of the striated musculature about twice as strong as etilefrine hydrochloride (E, Effortil ) for the same increment in central venous pressure. This and the additive effects of both agents on central venous pressure suggested that E may constrict primarily splanchnic capacitance vessels, a hypothesis, that was tested here by looking at the regional distribution of 99Tc -marked erythrocytes in healthy volunteers. With the subjects supine under a gamma camera the radioactivity was recorded along with central venous pressure, heart rate, and arterial pressure and evaluated for various regions. E was infused twice at a rate of 5 micrograms/kg per minute before and after the injection of DHE (7.5 micrograms/kg). E reduced strongly and selectively the radioactivity in the splanchnic area, not however in skeletal muscle. The reverse held for DHE. Both agents increased the counting rates in the thorax and also central venous pressure, effects which were additive when the two drugs acted together. E preferentially expels blood from the splanchnic vasculature, but DHE from skeletal muscle. The effects add and redistribute blood in favour of the intrathoracic circulation so that the combination of the two agents could be used to advantage for the treatment of cardiac filling disturbances.