Protocolo para avaliaÃÃo do efeito da radiaÃÃo ionizante na atividade da glicoproteÃna -P

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Changes on P-glycoprotein (P-gp) activity after individual exposure to ionizing radiation may be crucial to the effectiveness of treatments which employ radiotherapy prior to chemotherapy. In this context, the aim of this work was to establish a protocol to evaluate the ionizing radiation effect on P-gp activity. Peripheral blood samples of five healthy individuals were separately irradiated in vitro, from a cobalt-60 source, in order to receive 0,5 and 2,0 Gy, being kept one no-irradiated sample as control. P-gp activity was analyzed for CD4 and CD8 T lymphocytes, through rhodamine 123-efflux assay by flow cytometry (total 60 readings), and scored as percentage and mean fluorescence index. The comparison of mean P-gp activity among groups of control and irradiated samples indicated that there is no influence of irradiation on P-gp activity in T lymphocytes. However, in a subject-by-subject evaluation, were pointed out changes on P-gp function in irradiated samples, for some cases and absorbed doses. The simultaneous analysis of percentage and mean fluorescence index parameters showed to be essential for the intercomparison of irradiated and control samples of each donor. As base on results obtained, the proposed protocol was considered adequate for P-gp activity assessing after radioactive stress, configuring it as important prognostic factor to right patient-specific treatment, particularly for individuals that may present radioinduced multidrug resistance

ASSUNTO(S)

radiotherapy flow cytometry engenharia nuclear p-glycoprotein activity radioterapia resistÃncia a mÃltiplas drogas glicoproteÃna-p anÃlise funcional functional analysis multidrug resistance citometria de fluxo

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