A technique that can measure
tumor blood flow easily, accurately and economically is required to study
tumor angiogenesis and angiogenesis inhibition. Using
dye extraction colored
microspheres, we measured
tumor blood flow in Sato lung
carcinoma (SLC) and
ascites hepatoma LY80 in rats. Colored
microspheres were infused into
tumor-bearing rats via a
catheter in the left ventricle. After removal of the
tumor and the liver, the tissue samples were dissolved, and the
microspheres were isolated.
Dye was extracted, and the
dye concentration was quantified by spectrophotometry. The
dye concentration per gram of
tumor was compared with that per gram of liver as follows (AU = absorbency units): [AU per gram of
tumor] / [AU per gram of liver] X 100 = (%).
Tumor blood flow corrected for wet weight was calculated as follows: [blood flow to
tumor] = [AU per gram of
tumor] X [reference withdrawal rate] / [AU per gram of reference blood].
Tumor blood flow rate was divided by
tumor weight to yield ml. min-1g-1. The
tumors were also examined histologically, and casts of the
tumor vasculature were prepared with
silicone rubber. Blood flow 2 weeks after
transplantation was equivalent to 1/10 and 1/2 at 1 week in SLC and LY80
tumors, respectively (SLC, P=0.009, n=10; LY80, P=0.05, n=10). These decreases in
tumor blood flow were associated with underlying pathological and vascular change. Blood flow in LY80
tumors negatively correlated with
tumor volume (P=0.009, n=10). We concluded that the colored
microsphere method, initially developed to measure organ blood flow, is also useful for estimating
tumor blood flow in rats.