BLOOD-FLOW AND LEUKOCYTE ADHESIVENESS ARE REDUCED IN THE MICROCIRCULATION OF A PERITONEAL DISSEMINATED COLON-CARCINOMA

Dynamic behavior of leukocytes in the microcirculation of solid tumor tissue was visualized using a fluorescent labeling technique combined with the use of a real-time confocal laser-scanning microscope (CLSM) system. Colon tumor cells (RCN-9) were inoculated into the peritoneal cavity of male Fischer 344 rats. Tumor-free rats were similarly inject ed with physiological saline (intraperitoneally). Ten days after tumor inoculation, the mesentery was exteriorized and subjected to vital mi croscopic observation under the CLSM system. Leukocytes were labeled w ith rhodamine 6G (100 mu g kg(-1), intravenously), and their behavior within the microvessels (10-30 mu m in diameter) was analyzed both in the solid tumor tissues and the normal mesentery. Wall shear rate was calculated from the measured values of vessel diameter and erythrocyte flow velocity. In tumor microvasculature of tumor-bearing rats, the c enterline erythrocyte velocity (0.73+/-0.58mms(-1), mean +/-standard d eviation) and wall shear rate (210+/-151(-1)) were significantly lower than those of the tumor-free rats (1.27 +/-0.83 mm s(-1), 344+/-236 s (-1), respectively). Despite such re duced flow conditions, flux of th e rolling leukocytes as well as density of the adhered leukocytes both decreased significantly in tumor microvasculature as compared with no rmal controls. The methods developed in this work show promise in impr oving our understanding of tumor biology and pathophysiology. (C) 1998 Biomedical Engineering Society.