AGTR1 and infarction: In conclusion, P-MSN/miR199a-5p nanoparticles target ischemic myocardial tissues, releasing miR199a-5p targeting AGTR1 to reduce oxidative damage in the early post-infarction period of myocardial infarction; and targeting MARK4 to affect the long-term myocardial contractility, thus achieving long-term infarction repair effects (Fig. 8).