Continuous angiotensin-(1-7) infusion improves myocardial calcium transient and calcium transient alternans in ischemia-induced cardiac dysfunction rats

The aim of this study was to evaluate the impact of Ang-(1-7) on calcium transient (CaT) in cardiomyocytes during the pathogenesis of heart failure. Cardiac dysfunction was induced by ligation of left anterior descending coronary artery in adult SD rats. Randomly selected rats were ligated and continuously infused with Ang-(1-7) [HF + Ang-(1-7) group] or saline (HF + saline group) via osmotic minipumps. After 28 days, hemodynamic parameters, the CaT, and the heart rate threshold of CaT alternans (CaT-Alt) were measured. Continuous Ang-(1-7) treatment could attenuate the impairment of cardiac function following LAD ligation. The amplitudes (F/F0) and 50%/90% recovery time of CaT were significantly different among HF + saline, HF + Ang-(1-7) and Sham-operated group. Compared to the Sham-operated group, the HF + saline group showed decreased CaT amplitude, and a prolonged 50%/90% CaT recovery time; Ang-(1-7) significantly improved these abnormalities. Compared with Sham-operated group, heart rate thresholds of CaT-Alt significantly reduced in HF + saline group, and Ang-(1-7) partly restored it. These findings indicate that Ang-(1-7) attenuates the CaT disturbance and increases the heart rate threshold of CaT-Alt during the pathogenesis of ischemic heart failure.