Efeitos da administração crônica da digoxina sobre a contratilidade e o transiente de cálcio no miocárdio de ratos submetidos ao treinamento físico intervalado

Abstract

The objective of this study was to investigate the effects of chronic digoxin administration on contractility and calcium transient in rats submitted to interval physical training (TFI). METHODS: Twenty-eight Wistar rats, 60 days distributed in: control (C), trained (T), digoxin (DIGO) and trained + digoxin (TDIGO) were used. Digoxin was administered via oro-gastric gavage (30μg / kg / day) for 75 days. TFI was on a treadmill (1 h / day, 5 days / week, 60 days) at 80% of maximum speed (Vmax) for 8 minutes and 20% of Vmax for 2 minutes. Vmax was determined in the maximum progressive effort test. Left ventricle samples were used for the expression of Serca 2a, phospholamban and calcineurin proteins. Calcium contractility and transient were performed on isolated cardiomyocytes. Results: Digoxin and training did not affect the expression of the proteins Calcineurin, Serca 2a and Fosfolambam. TFI increased the shortening (%) and the amplitude of the calcium transient and reduced the rate of cardiomyocyte relaxation. Digoxin increased the rate of shortening and relaxation, but did not affect the calcium transient of cardiomyocytes. There was no interactive effect of digoxin and TI on contractility and transient calcium. Conclusion: Interval training provided a diastolic dysfunction in the contractility of cardiomyocytes, while digoxin reversed this dysfunction. This effect does not appear to be related to cytosolic calcium.