Background: Besides its “classical” neurotransmitter function in the central and peripheral nervous systems, serotonin, or 5-hydroxytryptamine (5-HT) is also a local hormone in a number of tissues, including those of the GI tract. Radiation is known to be able to disrupt certain functions of the tract, modulated by 5-HT-signaling pathways, or the serotonin receptors themselves. Aim: The present investigation focused on clarifying the nature and extent of influence of an accelerated electron beam with energy of 9 MeV on the serotonergic mediation of healthy smooth muscle gastric tissue of rats following total body irradiation of the animals. Materials and methods: The study involved a control group and two experimental groups of animals exposed to 1 and 5 Gy, respectively, using Siemens Primus S/N 3561. Circular smooth muscle tissues were isolated from rats 1 hour and 18 hours after they were exposed to 1 and 5 Gy and also 5 days after irradiation from the rats that received a dose of 5 Gy in order to investigate the action of exogenous serotonin at increasing concentrations from 10-8 to 10-4 mol/l. The contractile reactivity of each group SM preparations was registered isometrically. Results: Electron beams with energy of 9 MeV did not damage the contractile apparatus of gastric SM of rats and had a stimulating effect on contractility resulting from rapidly developing processes (1 hour) or later occurring once (5 days). Conclusions: Difference was observed in the importance of the factors of received dose, lapse of time from irradiation to investigation of SM tissues, and exogenous 5-HT concentration for the changes in SM reactivity in serotonin-induced tonic and phasic responses.

BACKGROUND: Prothrombotic tendency is characteristic of tumors. The aim of the study is to investigate the changes in the laboratory parameters for coagulation and fi brinolysis, namely in fi brinogen, thrombinantithrombin complex (ТАТ), tissue factor (ТF), prothrombin fragment (F1+2), antithrombin III (AT III), D-dimer and screening coagulation tests in cancer patients before initiation of chemotherapy. MATERIALS AND METHODS: Levels of F1+2, fi brinogen, ТАТ, AT III, TF, D-dimer, PT, aPTT and TT were measured baseline in 80 patients with breast and lung cancer before systemic treatment. The same parameters were investigated in 65 healthy volunteers. TF, ТАТ, F1+2 were measured by ELISA; AT III, D-dimer, fi brinogen and screening coagulation tests were measured by automated coagulation system Sysmex CS 2000i. RESULTS: Levels of F1+2, fi brinogen, ТАТ, TF, and D-dimer in cancer patients were signifi cantly higher than those in the control group, while the levels of ATIII activity were signifi cantly lower (p < 0.001). The highest area under the ROC curve was for D-dimer, which made it a good marker for the risk of thrombosis. CONCLUSION: Higher levels of TF, ТАТ, F1+2, fi brinogen and D-dimer and lower activity of АТ III in cancer patients support our hypothesis of an association between malignant disease and coagulation disorders. Cancer patients are at an increased risk of thrombosis wherefore antithrombotic prophylaxis may be considered (Tab. 6, Fig. 2, Ref. 34).