Cardiac output redistribution induced by noradrenaline in two murine tumor models.

The response of tumor vessels to vasoactive substances could provide useful information on experimental tumor biology. We have studied the effects of noradrenaline (20 micrograms/kg i.v.) on cardiac output (%CO) distribution in C57BL/6J mice bearing syngeneic Lewis lung carcinoma (3LL) and BALB/c mice with JW sarcoma (JWS). Mice were studied at different stages during tumor growth using microspheres labeled with 57Co (basal determination) or 58Co (after noradrenaline or saline). In control C57BL/6J mice noradrenaline induced a redistribution of CO, with an increase in the heart and brain and a decrease in the kidneys and hind limb muscle CO fractions (%CO). In 3LL-bearing mice the %CO to the tumor was not changed by noradrenaline 1 week after implantation but was significantly less after 2 and 3 weeks. %CO to the total lung tissue or to isolated metastases did not change after noradrenaline. In control BALB/c mice noradrenaline increased the %CO to the brain and decreased that to the kidneys and hind limb muscle. In JWS-bearing mice the %CO to the tumor was reduced 2 weeks after implantation, was not changed after 4 weeks and was increased after 6 weeks. These results suggest that tumor vessel reactivity to a vasoactive substance may change markedly during various phases of tumor growth and may differ in different experimental models.