科研之友
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摘要
Angiotensin-(1-7) [Ang-(1-7)] has been proved to have cardioprotective effects. However, the effects of this peptide on cardiac arrhythmias in vivo and details regarding its mechanism of action are still undetermined. The aim of this study was to investigate the protective effects of Ang-(1-7) against cardiac arrhythmias, its in vivo effects and cellular mechanism of action. We analysed the ECG upon inducement of arrhythmias in vivo in rats using a combination of halothane and adrenaline. To analyse the effects of Ang-(1-7) on cells, fresh mouse ventricular cardiomyocytes were isolated. The cardiomyocytes were superfused with a solution containing halothane and isoprenaline as a model to induce arrhythmias and used in three different approaches, namely a contractility assay, patch-clamp technique and confocal microscopy. The in vivo ECG showed that the injection of Ang-(1-7) (4 nm I.V.) significantly reduced cardiac arrhythmias [before, 49 +/- 43 arrhythmic events versus after Ang-(1-7), 16 +/- 14 arrhythmic events]. This effect was blocked by injection of A-779 and l-NAME, without changes in haemodynamic parameters. In addition, contractility experiments showed that Ang-(1-7) significantly decreased the number of arrhythmic events without changing the fractional shortening. This protection was associated with a reduction of the action potential repolarization and membrane hyperpolarization. Moreover, Ang-(1-7) decreased the number of calcium waves without any changes in the amplitude of the calcium transient, despite a significant reduction in the decay rate. Our data provide new evidence on the cellular mechanism together with an in vivo demonstration of the antiarrhythmic effects of Ang-(1-7).
- 出版日期2016-12-1
