Acute effects of granulocyte colony-stimulating factor on early ventricular arrhythmias after coronary occlusion in rats

OBJECTIVES: To evaluate the acute effects of colony-stimulating factor (G-CSF) on ventricular arrhythmias after coronary occlusion in rats. MATERIALS AND METHODS: Male Wistar rats (10 weeks) received G-CSF (100 μg.kg(-1)) or vehicle. Thirty minutes later, animals were infarcted by coronary occlusion under artificial respiration. Electrocardiogram was monitored for 30 min to evaluate ventricular arrhythmias. RESULTS: G-CSF treatment reduced the number of premature ventricular beats and the number and duration of ventricular tachycardia. The incidence of ventricular fibrillation was significantly reduced by G-CSF (MI-Cont: 11.2 ± 2.4 vs. MI-GCSF: 5.4 ± 1 events; P < 0.05). However, total duration of ventricular fibrillation was not altered (MI-Cont: 84 ± 16 vs. MI-GCSF: 76 ± 13 sec). CONCLUSIONS: Acute administration of G-CSF before coronary ligature in rats reduces the incidence of ventricular premature beats and ventricular tachycardia, suggesting a possible direct electrophysiological effect of this cytokine independently of its genomic effects. However, the data suggest that G-CSF treatment may affect the spontaneous recovery from ventricular fibrillation. Acute G-CSF administration acts directly on cardiac electrophysiology, different from chronic treatment.