CHARACTERIZATION OF THE SPECIFIC RESPONSE TO SEROTONIN OF MOUSE TUMOR-FEEDING ARTERIOLES

Purpose: To investigate the role of tumour versus non-tumour factors i n the specific response to serotonin (5-HT) of tumour-feeding arteriol es (TFA). Materials and methods: Using mouse models of intra-vital mic roscopy, the response to topical administration of 5-HT was studied in arterioles feeding tumours: fibrosarcoma (Meth A), murine mammary ade nocarcinoma (EMT6) and human colo-rectal carcinoma (HRT18) intra-cutan eously implanted. Results: For all types of tumour, 5-HT induced a far more pronounced constriction of TFA than of control arterioles. The p resence of a tumour implanted in the connective tissue between the ski n and the cremaster muscle also affected the reactivity of muscle arte rioles. Conversely, the response to serotonin by neovessels grown afte r implantation of an exogenous clement under the skin did not differ f rom that of control arterioles. Conclusions: Changes in reactivity to serotonin were not dependent on the type of tumour implanted in the sk in and were not present for a non-tumour implant. The presence of the tumour can alter the reactivity of vessels from tissue in contact with the tumour even if these vessels did not feed the tumour. This phenom enon is local and was not found in the vessels at a distance from the tumour.