The blood supply of experimental liver metastases. V. Increased tumor perfusion with epinephrine.

The effects of epinephrine on the vascular perfusion of solitary Walker tumors implanted in the liver were studied in Sprague-Dawley rats. Colored silicone rubber (Microfil) solutions were injected into the arterial and portal circulations in each animal, and specimens were studied under a stereomicroscope. Internal vascular volume was calculated on the basis of the interference of light passing through the central portions of the tumors by Microfil-filled vessels. Intraarterial epinephrine, in doses of 100 or 10 micrograms, markedly increased vascular perfusion in the encircling plexus and the internal tumor circulation compared with control animals. Internal vascular volume was significantly increased from 9.4 percent in controls to 22.5 percent in epinephrine-treated animals. Increased perfusion was also seen when epinephrine was administered through the portal system, and in larger tumors after intraarterial administration. Internal tumor vessels were capillary-like in appearance.