Lymph Flow from Murine Footpad Tumors before and after Sublethal Hyperthermia

The effect of local hyperthermia (43.5°C for 1 h) on lymph flow from B16-F10 tumor-bearing foot pads of C57BL/6 mice was measured by monitoring the clearance of${}^{99{\rm m}}{\rm Tc}\text{-labeled}$ human serum albumin. The foot was represented by a single-compartment model enabling a quantitative computation of lymphatic flow from the tumor to regional lymph nodes. Lymphatic flow from untreated tumors was$0.0059\pm 0.0011\ {\rm ml}/{\rm min}\ {\rm cm}^{3}$ compared to$0.0118\pm 0,0027\ {\rm ml}/{\rm min}\ {\rm cm}^{3}$ lymphatic flow from tumors immediately following heating. Morphological alterations in tumor blood vessels result in their high vascular permeability. The increase in lymphatic clearance from tumors after sublethal hyperthermia is compatible with the increase in interstitial fluid formation in tumors based on Starling's Law.