Resting host and tumor perfusion as determinants of tumor vascular responses to norepinephrine.

Blood flow determinations and arteriograms were obtained in rat (Walker carcinoma) and rabbit (V2 carcinoma) liver tumors at rest and after norepinephrine administration. Resting tumor blood flow exceeded resting hepatic flow in both models, and both tumors responded with vasoconstriction and reduced blood flow. In tumors and the surrounding normal host tissue, the greater the perfusion prior to drug administration, the greater is the response (decrease in perfusion) to the vasoconstrictor. Although tumor perfusion decreased after vasoconstrictor, post-norepinephrine angiograms revealed an improved diagnostic image because of the enlarged but unresponsive tumor feeder vessels, persistent tumor blush, and simultaneous vasoconstriction in the normal liver. In these models, improved tumor visualization resulted even though a decrease in tumor blood flow had occurred. The angiographic image is related therefore to the lack of vasoconstriction in the tumor feeder vessel, which has, however, a decreased blood flow and the correspondingly greater volume of normally constricting hepatic arteries which results in a marked decrease in the background of vessels upon which the tumor image is superimposed.