Microcirculatory effects of hyperthermia and 5-fluorouracil in the skin of nude mice.

ABSTRACT

During cancer chemotherapy physical manipulation of skin perfusion by hyperthermia can limit therapeutic efficacy. Because it is important to know microcirculatory responses to those forms of treatment, we used the ear of the lightly or not at all anesthetized nude mouse (rnü/rnü). To test, if whole body hyperthermia (WBH) and 5-fluorouracil (5-FU) acutely affect skin microvessels, we applied red light (group 1). 5-FU was injected prior to WBH, to test for effects of 5-FU on WBH (group 2). Respiratory rate increased and medium sized and small arterioles constricted during WBH in both groups and cutaneous perfusion decreased. 5-FU did not change these results. There were more leucocytes rolling along the vessel wall of small and medium-sized venules after 5-FU treatment (compared to BL). Our data suggest that activation of sympathetic tone by an external heat source compromises skin perfusion and could decrease the amount of cytostatic agents to that organ during WBH. Finally, there is more intense interaction among leucocytes and endothelial cells omit in response to 5-FU.