Perfusion characteristics and norepinephrine reactivity of human renal carcinoma

Kidneys, surgically removed due to carcinoma, were subjected to perfusion in vitro. The perfusion distribution was studied by means of labeled microspheres injected during maximal vascular dilation and during two different norepinephrine concentrations. The perfusion concluded with injection of barium sulfate. Two-mm-thick slices of tissue were autoradiographed and microangiographed for visualization of perfusion and distribution of vascular density, respectively. Multiple specimens from tumor and cortical tissues were subjected to quantitative perfusate flow analysis. In spite of regionally high vascular density, perfusion through "normal-sized" capillaries was very low in tumor tissue as compared to cortex (during maximal dilation, one-tenth of the cortical flow). During moderate norepinephrine infusion, the perfusate flow decreased, and the resistance of the cortex increased. The flow to tumor tissue increased while the vascular resistance remained constant. During higher norepinephrine concentrations, the flow was redistributed; i.e., the cortical flow increased while that of the tumor decreased, due to a marked increase in tumor vascular resistance while the cortical tissue showed a very moderate rise in resistance. The thin-walled tumor vessels might be collapsed under a high tissue pressure at low perfusion pressures. At higher perfusion pressure, the vessels might open up, and contractile activity may not be expressed until then. The tumor vascular resistance increased 3 to 4 times, while that of cortex showed a 7-fold increase. Indications that a considerable fraction of the perfusate passes arteriovenous passages larger than 15 micron were obtained in individual experiments, this fraction increasing upon norepinephrine infusion.