In the present study, the intraplantar injection of 105 EAT cells in rats induced a tumor and a progressive increase of paw edema which reached a plateau on the 6th day after inoculation. After this time period, the paw edema did not increase further and necrotizing tissues developed at the inoculation site (data not shown). Treatment of rats with the B1 antagonist R-954 for 6 days significantly reduced (51.4%) the edema formation. When the treatment was prolonged for more than 6 days, animals did not develop necrotizing tissues (data not shown). Similar results were obtained with vincristine (52.5% reduction) used as positive control (Fig. 3). This study presents for the first time

the antitumoral activity of a new bradykinin B1 receptor antagonist (R-954) on ascitic and solid tumors induced by Ehrlich cell inoculation in Trametinib ic50 mice and rats. The results showed that the inoculation of Ehrlich tumor cells in mice induced the formation of large ascitic tumors which were maximal after

9–10 days. The size of the tumor did not increase further in the following days. Although only one animal died on the 9th day after the inoculation, the death toll increased to 20% the following day and to Selleck Epacadostat 50% the 15th day. The treatment of Ehrlich tumor-bearing mice with R-954 during 10 days after tumor inoculation resulted in a significant reduction of ascitic volume which clearly suggested that the B1 receptors was involved in the growth of this invasive tumor. At the effective doses used, compound R-954 showed no signs of general toxicity; the mouse weight gain was normal and internal organs did not show abnormalities (data not shown). In the group of animals which was given R-954 only one animal died Fenbendazole during the full experimental period (after 15 days of treatment).

This is in sharp contrast to the effects of the standard anti-cancer drugs vincristine used for comparison. At the doses of vincristine used to obtain the reported tumor inhibition, the mice were sick and did not gain weight. Ehrlich tumor has been used as a transplantable tumor model to investigate the antineoplastic effects of several pharmacological agents. Following the intraperitoneal inoculation of Ehrlich tumor cells, the ascitic volume and number of tumor cells were shown to increase progressively [55]. Ascitis in the peritoneal cavity is the result of tumor-induced inflammation as shown by peritoneal vascular permeability increase and release of several inflammatory mediators [14] and [15]. The exact mechanisms of the inhibitory effect of R-954 are still unknown but unpublished results showed that this compound did not have cytotoxic activities against up to 40 types of cancer cells. Its selective inhibitory action on tumor growth was suggested to be due to the inhibition of angiogenesis elicited by inflammatory mediators such as bradykinin and others formed during the development of the tumor.