Measurement of capillary filtration coefficient in a solid tumor.

The net transvascular filtration rate, JF (ml/min/100 g), in an isolated, RBC-free perfused R3230AC mammary adenocarcinoma tumor was measured using a gravimetric method whereby changes in tissue weight over time were monitored. From the gravimetric measurements of JF following changes in venous pressure, the capillary filtration coefficient (ml/min/mm Hg/100 g) was found to be 2.2 (range, 0.8-2.8), i.e., 10 to 1000 times higher than those found in several normal tissues and within the range of those reported for glomerular capillaries. These measurements of capillary filtration coefficient are consistent with elevated tumor interstitial fluid pressure, interstitial fluid flow, and peritumor edema.