RESUMO
PURPOSE: The aim of this study was to investigate the impact of granulocyte-colony stimulating factor (G-CSF) administration on cardiac function of rats with chronic myocardial infarction through two different protocols: high dose short term and low dose long term protocols. METHODS: Wistar rats were submitted to MI surgery and after 4 weeks they received recombinant human G-CSF (Filgrastim) or vehicle subcutaneously. We tested the classical protocol (50 microg/kg/day during 7 days) and the long term low dose treatment (four cycles of 5 days of 10 microg/kg/day). Cardiac performance was evaluated before, 4 and 6 weeks after G-CSF injections by electro- and echocardiography, hemodynamic and treadmill exercise test. RESULTS: All infarcted groups exhibited impaired function compared to sham operated animals. Moreover, all cardiac functional parameter were not different between G-CSF and Vehicle group at resting conditions as well as after treadmill exercise stress test, despite intense white blood cell mobilization in both protocols at all time points. Hypertrophy was not different and infarct size was similar in histological analysis CONCLUSIONS: These data clearly show that G-CSF treatment was unable to restore cardiac function impaired by myocardial infarction either with classical approach or long term low dose administration.