Experimental studies on the role of the portal circulation in hepatic tumor vascularity

Whereas the predominance of arterial circulation in the nourishment of liver tumors has been well established, the portal circulation also appears to play a significant role under some circumstances. Studies were performed on Sprague-Dawley rats with Walker carcinosarcomas implanted in the liver, and vascularity was identified by portal and arterial injection of pigmented silicone rubber (Microfil, Canton Bio-Medical Products, Boulder, CO). Experimental groups consisted of animals with hepatic artery ligation at time of tumor implant with Microfil injection 3 or 7 days later, and animals with hepatic artery ligation 3 or 7 days after tumor implantation with immediate Microfil injection. In all groups, portal filling of tumor microcirculation was identified. Histologic examination of tumors in control animals randomly demonstrated portally injected Microfil in vessels within the substance of the tumors. These studies confirm earlier experiments demonstrating a portal component in the microcirculation of liver tumors, and justify attempts to use the portal circulation in anticancer therapy.